Disk fusion implant

ABSTRACT

An implant strip is disclosed. In some cases, the prosthesis can take the form of an implant strip that may be implanted through the use of a surgical procedure that minimizes incision sizes and may be considered less invasive than typical spinal implant procedures. The implant strip includes provisions for implantation, including teeth, spacing provisions, and various shapes.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Patent Publication Number US2009/0012623 (U.S. patent application Ser. No. 12/118,503, filed May 9,2008), which is a continuation-in-part of U.S. Pat. No. 7,922,767,issued Apr. 12, 2011 (U.S. patent application Ser. No. 11/774,584, filedJul. 7, 2007), both of which are herein incorporated herein by referencein their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to implantable prostheses and inparticular to a spinal implant strip including a selectively appliedbone growth promoting agent.

2. Description of Related Art

Spinal fusion implants have been previously proposed. In some cases,spinal fusion implants are embedded between adjacent vertebrae,partially or fully replacing the tissue disposed between the vertebrae.

One type of spinal fusion implant is the threaded spinal implant(commonly referred to as a spinal cage). This type of prosthesis isdisclosed in Michelson (U.S. Pat. No. 6,264,656), the entirety of whichis incorporated by reference. The threaded spinal implant is insertedbetween two adjacent vertebrae and is incorporated into the fusion ofthe bone along this portion of the spine.

Brantigan (U.S. Pat. No. 4,834,757) discloses plugs, used as spinalfusion implants, the entirety of which is incorporated by reference. Theplugs are rectangular with tapered front ends and tool receiving rearends. Generally, the plugs may be used in a similar manner to the spinalcages of Michelson. As with the spinal cages, the plugs may be insertedbetween adjacent vertebrae. The plugs may include nubs that behave liketeeth, countering any tendency for the plugs to slip between thevertebrae.

Generally, the spinal fusion implants disclosed require invasive surgeryfor implantation. Furthermore, these spinal fusion implants rigidly fixtwo adjacent bones together and do not allow for any motion. There is aneed in the art for a type of spinal fusion implant that may beimplanted through a minimally invasive procedure. There is also a needfor fusion implants that can potentially accommodate motion.

SUMMARY OF THE INVENTION

Modifications for an implant strip for implantation is disclosed. In oneaspect, the invention provides a spinal prosthesis, comprising: animplant strip configured for insertion between two vertebrae; theimplant strip comprising a first portion having a first axial height anda second portion having a second axial height; and where the first axialheight is greater than the second axial height.

In another aspect, the implant strip includes an edge that has a coiledshape selected from the group consisting essentially of a wedge shape, aconvex shape, and a concave shape.

In another aspect, the first portion is associated with a crest of theimplant strip.

In another aspect, the second portion is associated with a trough of theimplant strip.

In another aspect, the second portion is a first end of the implantstrip associated with an inner coil.

In another aspect, the first portion is a second end of the implantstrip associated with an outer coil.

In another aspect, the first portion is a first end of the implant stripassociated with an inner coil.

In another aspect, the second portion is second end portion of theimplant strip associated with an outer coil.

In another aspect, the invention provides a spinal prosthesis,comprising: an implant strip configured for insertion between twovertebrae; the implant strip forming a first coil and a second coil; aseparating portion disposed the first coil and the second coil; andwhere the separating portion contacts the first coil and the secondcoil.

In another aspect, the separating portion comprises a plurality ofprotrusions on a first surface of the implant strip.

In another aspect, the protrusions are associated with correspondingdivots on an opposing second surface of the implant strip.

In another aspect, an opposing second surface of the implant strip issubstantially smooth.

In another aspect, the separating portion is a polymer.

In another aspect, the thickness of the polymer varies over the lengthof the implant strip.

In another aspect, the invention provides a spinal prosthesis,comprising: an implant strip configured for insertion between twovertebrae; the implant strip comprising an edge; and where the edgeincludes a plurality of teeth.

In another aspect, the edge is an upper edge.

In another aspect, the edge is a lower edge.

In another aspect, a plurality of teeth is disposed on an upper edge anda lower edge.

In another aspect, the teeth have a configuration selected from thegroup consisting essentially of a saw-toothed shape, a rounded shape, asubstantially dull shape, a substantially sharp shape, irregularlyspaced teeth, and/or regularly spaced teeth.

In another aspect, the invention provides a spinal prosthesis,comprising: a dual implant strip configured for insertion between twovertebrae, the dual implant strip further comprising a first implantstrip and a second implant strip; and a spacer portion is disposedbetween the first implant strip and the second implant strip and whereinthe spacer portion is configured to attach the first implant strip tothe second implant strip.

In another aspect, the spacer portion is made of a material differentthan a material of the first implant strip.

In another aspect, the invention provides a spinal prosthesis,comprising: a layered implant strip configured for insertion between twovertebrae, the layered implant strip further comprising a plurality ofimplant strips and a plurality of spacer portions; and where a spacerportion from the plurality of spacer portions is disposed between eachpair of adjacent implant strips from the plurality of implant strips.

In another aspect, the invention provides a spinal prosthesis,comprising: an implant strip including a first shape and a second shapeand wherein the first shape is different than the second shape; theimplant strip having the first shape prior to insertion; and where theimplant strip transforms from the first shape to the second shapefollowing the application of a signal.

In another aspect, the signal is selected from the group consistingessentially of heat signals, chemical signals, mechanical signals, andelectrical signals.

In another aspect, the invention provides a spinal prosthesis configuredfor insertion between two adjacent vertebrae, a first vertebrae and asecond vertebrae, comprising: an implant strip including a lateraldimension extending from a first lateral side portion to a secondlateral portion, and wherein the implant strip includes a longitudinaldimension extending down the length of the implant strip; and where thefirst lateral side of the implant strip is configured to engage thefirst vertebrae and wherein the second lateral side of the implant stripis configured to engage the second vertebrae; the implant strip having apre-formed shape comprising a first longitudinal portion of the implantstrip forming a first inner coil and a second longitudinal portion ofthe implant strip forming a second outer coil; and where the implantstrip has the pre-formed shape prior to implantation.

In another aspect, the implant strip includes n coils and wherein n canbe any real number greater than 1.

Other systems, methods, features, and advantages of the invention willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the invention, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 is an isometric view of a preferred embodiment of a patientundergoing surgery;

FIG. 2 is a plan view of a preferred embodiment of an intervertebraldisc;

FIG. 3 is a schematic view of a preferred embodiment of a healthyintervertebral disc and an intervertebral disc that has degenerated;

FIG. 4 is a plan view of a preferred embodiment of an implant strip;

FIG. 5-1 is a cross sectional view of a preferred embodiment of animplant strip with a bone growth promoting agent applied to the surface;

FIG. 5-2 is a cross sectional view of a preferred embodiment of animplant strip with a bone growth promoting agent that is selectivelyapplied to the surface;

FIG. 6 is a plan view of a preferred embodiment of an intervertebraldisc with a surgical tool and a dual catheter inserted;

FIG. 7 is a plan view of a preferred embodiment of an intervertebraldisc with an implant strip being inserted;

FIG. 8 is a plan view of a preferred embodiment of an implant stripfully inserted;

FIG. 9 is a plan view of a preferred embodiment of an intervertebraldisc including three implant strips;

FIG. 10 is a plan view of a preferred embodiment of an intervertebraldisc with a corrugated implant strip inserted;

FIG. 11 is a schematic view of a preferred embodiment of an implantdevice in a pre-deflection state and a post-deflection state;

FIG. 12 is a schematic view of a preferred embodiment of an implantdevice undergoing bending;

FIG. 13 is a schematic view of a preferred embodiment of an implantdevice undergoing translation;

FIG. 14 is a schematic view of a preferred embodiment of an implantdevice undergoing twisting;

FIG. 15 is an isometric view of a preferred embodiment of an implantstrip;

FIG. 16 is an isometric view of a preferred embodiment of an implantstrip that has coiled;

FIG. 17 is an isometric view of a preferred embodiment of a coiledimplant strip under axial force;

FIG. 18 is a plan view of a preferred embodiment of a section of animplant strip configured for axial deflection;

FIG. 19 is a plan view of a preferred embodiment of a section of animplant strip under axial load;

FIG. 20 is a plan view of a preferred embodiment of a section of animplant strip configured for axial deflection;

FIG. 21 is a plan view of a preferred embodiment of a section of animplant strip under axial load;

FIG. 22 is a plan view of a preferred embodiment of a section of animplant strip configured for axial deflection;

FIG. 23 is a plan view of a preferred embodiment of a section of animplant strip under axial load;

FIG. 24 is a plan view of a preferred embodiment of a section of animplant strip configured for axial deflection;

FIG. 25 is a plan view of a preferred embodiment of a section of animplant strip under axial load;

FIG. 26 is an isometric view of a preferred embodiment of an implantstrip with slots;

FIG. 27 is a cross sectional view of a preferred embodiment of animplant strip with slots;

FIG. 28 is a cross sectional view of a preferred embodiment of animplant strip with slots;

FIG. 29 is an isometric view of a preferred embodiment of a coiledimplant strip with slots;

FIG. 30 is a top view of a preferred embodiment of a coiled implantstrip with slots;

FIG. 31 is an isometric view of a preferred embodiment of an implantstrip undergoing axial deflection;

FIG. 32 is a plan view of two preferred embodiments of implant stripswith slots with a differing number of slots;

FIG. 33 is a plan view of two preferred embodiments of implant stripswith slots undergoing circumferential deflection;

FIG. 34 is a plan view of a preferred embodiment of an implant stripwith different slots;

FIG. 35 is a schematic view of a preferred embodiment of an implantstrip partially permanently deflecting;

FIG. 36 is a plan view of a preferred embodiment of a delivery deviceused for facilitating coiling of an implant strip;

FIG. 37 is a top down view of a preferred embodiment of a herniatedintervertebral disc;

FIG. 38 is a top down view of a preferred embodiment of a herniated discafter partial discectomy;

FIG. 39 is a top down view of a preferred embodiment of a herniated discwith an implant strip inserted;

FIG. 40 is a plan view of a preferred embodiment of an implant stripwith teeth disposed in a saw tooth pattern on an upper and lower edge;

FIG. 41 is an isometric view of a preferred embodiment of an implantstrip coiled with a saw tooth pattern on an upper and lower edge;

FIG. 42 is a preferred embodiment of an implant strip with roundedirregularly spaced teeth disposed on an upper and lower edge;

FIG. 43 is an isometric view of a preferred embodiment of an implantstrip coiled with rounded irregularly spaced teeth disposed on an upperand lower edge;

FIG. 44 is a plan view of an exemplary embodiment of an implant stripwith protrusions;

FIG. 45 is a plan view of an exemplary embodiment of a coiled implantstrip with protrusions;

FIG. 46 is a plan view of an exemplary embodiment of polymer applied toan implant strip;

FIG. 47 is a cross sectional view of an exemplary embodiment of animplant strip with an application of polymer;

FIG. 48 is an isometric view of an exemplary embodiment of a coiledimplant strip with an application of polymer;

FIG. 49 is a cross sectional view of an exemplary embodiment of a coiledimplant strip with an application of polymer;

FIG. 50 is a schematic view of an exemplary embodiment of an implantstrip coiling in a kidney shape;

FIG. 51 is a schematic view of an exemplary embodiment of two coiledkidney shaped implant strips;

FIG. 52 is a schematic view of an exemplary embodiment of an implantstrip coiling in an oval shape;

FIG. 53 is a schematic view of an exemplary embodiment of two coiledoval shaped implant strips;

FIG. 54 is a plan view of an exemplary embodiment of an implant stripwith a curvilinear shape on an upper and lower edge;

FIG. 55 is an isometric view of an exemplary embodiment of a coiledimplant strip configured with a wedge shape;

FIG. 56 is a cross sectional view of an exemplary embodiment of a coiledimplant strip configured with a wedge shape;

FIG. 57 is a plan view of an exemplary embodiment of a tapered implantstrip;

FIG. 58 is an isometric view of an exemplary embodiment of a coiledimplant strip configured with a concave shape on a top and bottomsurface;

FIG. 59 is a cross sectional view of an exemplary embodiment of coiledimplant strip configured with a concave shape on a top and bottomsurface;

FIG. 60 is a plan view of an exemplary embodiment of a tapered implantstrip;

FIG. 61 is an isometric view of an exemplary embodiment of a coiledimplant strip configured with a convex shape on a top and bottomsurface;

FIG. 62 is a cross sectional view of an exemplary embodiment of coiledimplant strip configured with a convex shape on a top and bottomsurface;

FIG. 63 is a schematic view of an exemplary embodiment of a possibleconfiguration of an implant strip using a plurality of provision sets;

FIG. 64 is a schematic view of an exemplary embodiment of a possibleconfiguration of an implant strip using a plurality of provision sets;

FIG. 65 is a schematic view of an exemplary embodiment of a possibleconfiguration of an implant strip using a plurality of provision sets;

FIG. 66 is an isometric view of an exemplary embodiment of an implantstrip comprised of two implant strips and a spacer portion;

FIG. 67 is a top down view of an exemplary embodiment of a coiledimplant strip comprised of two implant strips and a spacer portion;

FIG. 68 is a cross sectional view of an exemplary embodiment of a coiledimplant strip comprised of two implant strips and a spacer portion;

FIG. 69 is an isometric view of an exemplary embodiment of an implantstrip constructed with multiple materials;

FIG. 70 is a schematic view of an exemplary embodiment of an implantstrip configured with distinct portions;

FIG. 71 is a cross sectional view of an exemplary embodiment of animplant strip configured with distinct portions;

FIG. 72 is an isometric view of an exemplary embodiment of a coiledimplant strip with slots and an application of polymer;

FIG. 73 is a cross sectional view of an exemplary embodiment of a coiledimplant strip with slots and an application of polymer;

FIG. 74 is an isometric view of an exemplary embodiment of an implantstrip comprised of two implant strips, a spacer portion and anapplication of polymer;

FIG. 75 is a cross sectional view of an exemplary embodiment of acannula with an implant strip comprised of two implant strips, a spacerportion and an application of polymer;

FIG. 76 is a top down view of an exemplary embodiment of a coiledimplant strip comprised of two implant strips, a spacer portion and anapplication of polymer; and

FIG. 77 is a cross sectional view of an exemplary embodiment of a coiledimplant strip comprised of two implant strips, a spacer portion and anapplication of polymer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is an isometric view of a preferred embodiment of patient 1100 onoperating table 1102. In this embodiment, patient 1100 is experiencing asurgical procedure to insert a spinal prosthesis. In particular, back1104 of patient 1100 preferably includes first incision 1106 and secondincision 1108. In a preferred embodiment, first incision 1106 includesfirst tube 1110 and second incision 1108 includes second tube 1114.Preferably, first incision 1106 and second incision 1108 are both lessthan one inch long. It should be understood that the placement ofincisions 1106 and 1108 may be moved further together or closer apartand the location of incisions 1106 and 1108 in the current embodiment isonly meant to be exemplary.

Preferably, first tube 1110 and second tube 1114 may be inserted into anintervertebral disc disposed between two adjacent vertebrae. For thepurposes of this application, “disc” and “disk” have the same meaningand may be used interchangeably. FIG. 2 is a plan view of a singlevertebra, shown generally at 1200, and an associated intervertebral disc1202. (The anatomy shown in FIG. 2 is generally that of a lumbarvertebra, although the anatomy of thoracic, lumbar, and cervicalvertebrae is similar; therefore, FIG. 2 can be considered to illustratethe basic principles of thoracic, lumbar, and cervical vertebralanatomy.) The spinous process 1206 of the vertebra 1200 extends dorsallyand can typically be palpated and felt through the skin of the back.Also in the dorsally-extending portion of the vertebra 1200 are twotransverse processes 1208 and two mammillary processes and facet joints1212. A spinal canal 1214 (i.e., an opening) is provided in the vertebra1200. The spinal cord and nerves 1216 extend through the spinal canal1214 such that the spinal cord 1216 receives the full protection of thebony, dorsally-located spinous, transverse, and mammillary processes andfacet joints 1206, 1208, 1212. The vertebral body also protects thespinal cord and nerves 1216 ventrally. Periodically, nerves 1218 branchout from the spinal cord 1216 to innervate various areas of the body.The forward or ventral edge of the vertebral foramen 1221 is defined bythe vertebral body (not shown in FIG. 2), a bony, generally ellipticalshelf in front of which the intervertebral disc 1202 rests. FIG. 2 alsoillustrates the basic structure of the intervertebral disc 1202,including the annulus fibrosis 1222 and the nucleus pulposus 1224.

In some cases, an intervertebral disc 1202 may degenerate over time,requiring the need for a spinal disc implant. FIG. 3 illustrates apreferred embodiment of degeneration. In this embodiment, healthyintervertebral disc 302 is disposed between vertebrae 304. In this case,vertebrae 304 are separated by a distance D1 because of support providedby disc 302. Also shown in FIG. 3 is unhealthy intervertebral disc 306,which is disposed between vertebrae 308. In this case, vertebrae 308 areseparated by a distance D2 that is much smaller than distance D1 becauseof the degeneration of disc 306.

If an intervertebral disc has failed or degenerated, a typicalcorrection is a surgical procedure to remove some or all of theintervertebral disc. Following this, a spinal prosthesis may be insertedin order to facilitate fusion of the vertebrae adjacent to the failedintervertebral disc. In a preferred embodiment, surgery may be performedin a manner that limits the size of the incisions needed to insert aprosthesis. Preferably, a spinal prosthesis includes provisions for easyinsertion via a small incision in the back.

In some cases, a vertebral body could also be fully or partiallyreplaced using a spinal prosthesis. The following detailed descriptionrefers to the replacement of an intervertebral disc, however in otherembodiments these same principles could be applied to a spinalprosthesis configured to replace a vertebral body.

FIGS. 4 and 5 illustrate a preferred embodiment of implant strip 1400.Generally, implant strip 1400 may be a long thin strip. Preferably,implant strip 1400 has a length L1 much greater than a width W1.Additionally, the thickness T1 of implant strip 1400 is preferably smallcompared to both the length and the width of implant strip 1400. In someembodiments, length L1 may be between 1 cm and 100 m. In someembodiments, width W1 may be between 2 mm and 20 cm. In someembodiments, thickness T1 may be between 0.01 mm and 3 mm. It should beunderstood that if a vertebral body is being replaced, the thickness ofimplant strip 1400 could be much larger than the values discussed here.

As implant strip 1400 preferably has a relatively small profile, it maybe inserted into smaller incisions, such as those shown in FIG. 1.However, to provide adequate support to the adjacent vertebrae, implantstrip 1400 may preferably be packed tightly into intervertebral disc1202. In some embodiments, the packing of implant strip 1400 may betight or loose depending upon mechanical properties of implant strip1400. For this reason, implant strip 1400 preferably includes provisionsfor conforming to a packed shape once it has been inserted intointervertebral disc 1202.

Generally, implant strip 1400 may be constructed of a material includingmetal. In some embodiments, implant strip 1400 may be a shape memoryalloy. In some embodiments, implant strip 1400 may be made of a titaniumalloy. In other embodiments, implant strip 1400 may comprise acombination of one or more materials including, but not limited to,cobalt chrome (CoCr), stainless steel, Nitinol, polymers, biologicalmatrices, ceramics, or any biocompatible material. In a preferredembodiment, implant strip 1400 may be made of a material includingtitanium.

In some cases, a stainless steel alloy may be used as a coiling spring.This arrangement is useful because such alloys low fatigue and highfatigue resistance. Additionally, these alloys may have a high returnforce. Additionally, using a stainless steel alloy allows for increasedcorrosion resistance.

Preferably, implant strip 1400 may include provisions for changingshape. In some embodiments, implant strip 1400 may be manufactured at anelevated temperature with a first shape. Following this, implant strip1400 may be cooled and formed into a second shape. Finally, as implantstrip is placed in temperature ranges of 90-100 degrees Fahrenheit, itmay revert back to the first shape. In a preferred embodiment, the firstshape is a spiral coil and the second shape is a long rectangular strip.

In some embodiments, implant strip 1400 may include provisions forpromoting bone growth, once it has been inserted into the intervertebraldisc region. In some embodiments, implant strip 1400 may include a bonegrowth promoting agent. In a preferred embodiment, implant strip 1400preferably includes bone growth promoting agent 1402 disposed along theentirety of its length. FIG. 5-1 is a cross sectional view of implantstrip 1400 with bone growth promoting agent 1402 disposed along itsentire outer surface 1401.

In some embodiments, bone growth promoting agent 1402 may be selectivelyapplied to one or more portions of implant strip 1400 or may not beapplied at all. Preferably, as shown in FIG. 5-2, bone growth promotingagent 1402 may be applied to top surface 1403 of outer surface 1401.Likewise, bone growth promoting agent 1402 may also be applied to bottomsurface 1405 of outer surface 1401. Generally, any type of bone growthpromoting agent may be applied and in any pattern. Methods forselectively applying bone growth promoting agents have been previouslydisclosed in U.S. Patent Publication Number US 2008/0269893 (U.S. patentapplication Ser. No. 11/740,181, filed on Apr. 25, 2007, entitled“Prosthesis with a Selectively Applied Bone Growth Promoting Agent”),the entirety of which is hereby incorporated by reference.

Details of a preferred embodiment of a surgical procedure used to inserta spinal prosthesis of some kind are best understood with respect toFIGS. 6-8. The following embodiment comprises steps for inserting aspinal prosthesis using two tubes, however it should be understood thatin other embodiments, a single tube may be used for discectomy and/orimplantation. In this case, any parallel steps involving the use of twotubes simultaneously could be performed sequentially with a single tube.In particular, steps using a camera and/or light inserted through onetube and a spinal tool through a second tube may be accomplished byusing a single tube incorporating a light and/or camera at the peripheryof the tube or just outside of the tube.

In a first step, first tube 1510 and second tube 1514 may be insertedinto intervertebral disc 1202. Generally, one tube may be used for asurgical tool, while the second tube may be simultaneously used toinsert a fiber optic camera into one of the incisions to give thesurgeon a clear view of the intervertebral disc region. In someembodiments, first tube 1510 and second tube 1514 may be cannulae. Thecross sectional shape of tubes 1510 and 1514 may be any shape, includingoval-like, circular or otherwise round, as well as hexagonal or anypolygonal shape.

Following the insertion of first tube 1510 and second tube 1514, aseries of instruments may be used to remove portions of intervertebraldisc 1202 and score the endplates. In some embodiments, first surgicaldevice 1540 may be inserted into first tube 1510. First surgical device1540 may be a brush, burr, rasp, or a shaver. In a preferred embodiment,first surgical device 1540 may include flexible shaft 1542 and wirebrush tip 1544. Preferably, wire brush tip 1544 spins, removing portionsof intervertebral disc 1202.

In some embodiments, dual catheter 1550 may be inserted into second tube1514. Preferably, dual catheter 1550 may include first channel 1552 andsecond channel 1554. In some embodiments, first channel 1552 may includea fiber optic camera. With this configuration, the surgery may bevisualized by the surgeon using the fiber optic camera. Additionally,second channel 1554 may be configured to inject water and/or provide avacuum for removing debris. With this configuration, second channel 1554may be used to clean out cavity 1560, which is created as a portion ofintervertebral disc 1202 is removed. Once the necessary portions ofintervertebral disc 1202 have been removed, first surgical device 1540may be removed from first tube 1510.

Referring to FIGS. 7-8, implant strip 1400 may be inserted into cavity1560 once a portion of intervertebral disc 1202 has been removed. Aspreviously discussed, implant strip 1400 preferably has a materialstructure that allows it to change shape following insertion into cavity1560. In a preferred embodiment, implant strip 1400 is configured tocoil as it is exposed to temperatures between 90 and 100 degreeFahrenheit. In other embodiments, implant strip 1400 could coil due tonon-temperature dependent memory, such as occurs with a measuring tape.This could be achieved using a titanium implant strip, for example.

In this embodiment, first portion 1600 of implant strip 1400 has startedto coil as it is inserted into cavity 1560. Preferably, as implant strip1400 is further inserted through first tube 1510, the portion disposedwithin cavity 1560 may deform and coil as well. In a preferredembodiment, implant strip 1400 may be inserted in a manner that allowsimplant strip 1400 to coil around itself completely, as seen in FIG. 8.

Generally, implant strip 1400 may be configured to fill cavity 1560 ofintervertebral disc 1202 completely. For illustrative purposes, implantstrip 1400 is shown here to be coiled with large gaps between adjacentportions. However, in some embodiments, implant strip 1400 may coiltightly so that no gaps are seen. In a preferred embodiment, implantstrip 1400 may coil loosely to provide space or gaps between adjacent,radially spaced coils. This arrangement may help to facilitate bonegrowth to occur between the coils.

In an alternative embodiment, multiple implant strips may be used.Preferably, each implant strip may include a coiled shape, similar tothe shape of the previous embodiment. In some embodiments, each of theimplant strips may be disposed against one another. In some embodiments,each of the implant strips may be associated with different heights inorder to create lordosis.

FIG. 9 is a preferred embodiment including multiple implant stripsinserted within cavity 1560. In this embodiment, first implant strip1802, second implant strip 1804, and third implant strip 1806 have beeninserted into cavity 1560. Preferably, each of the implant strips 1802,1804, and 1806 may be inserted in an identical manner to the method usedto insert the implant strip of the previous embodiment. Generally, anynumber of implant strips may be inserted into cavity 1560.

Preferably, each of the implant strips 1802, 1804, and 1806 may beconstructed of a shape memory alloy. In some embodiments, the shapememory alloy may be a nickel titanium alloy. In other embodiments,implant strips 1802, 1804, and 1806 may comprise a combination of one ormore materials including, but not limited to, cobalt chrome (CoCr),stainless steel, Nitinol, polymers, biological matrices, ceramics, orany biocompatible material. In a preferred embodiment, implant strips1802, 1804, and 1806 may be made of a material including titanium.

In other embodiments, the structure of an implant strip may be modified.In some embodiments, an implant strip may include a slightly differentshape. In other embodiments, an additional material may be used inconjunction with the shape memory alloy of the previous embodiments.

FIG. 10 is a preferred embodiment of corrugated implant strip 1902,which has been inserted into cavity 1560. Preferably corrugated implantstrip 1902 includes small bends along its length. Preferably, corrugatedimplant strip 1902 may be inserted into cavity 1560 in an identicalmanner to the method used to insert the previously discussed implantstrips. As with the previous embodiments, it should be understood that abone growth promoting agent may be applied to corrugated implant strip1902. This arrangement allows for greater mechanical strength as well asfor facilitating increased bone growth into implant strip 1902. Byproviding increased surface area, this arrangement may facilitategreater bone growth and more rapid bone healing.

Preferably, corrugated implant strip 1902 may be constructed of a shapememory material. In some embodiments, the shape memory alloy may be anickel titanium alloy. In a preferred embodiment, corrugated implantstrip 1902 may be made of a material including titanium. Generally,corrugated implant strip 1902 may be made of any of the materialsdiscussed with respect to the previous embodiments of implant strips,including cobalt chrome (CoCr), stainless steel, Nitinol, polymers,biological matrices, ceramics or any biocompatible material.

Preferably, an implant device includes provisions for allowing fordifferent kinds of motion that may occur in a spine.

In some embodiments, an implant device may include provisions toaccommodate deflections in the axial direction. This may be a usefulfeature as axial forces may be applied to the implant strip by theadjacent vertebrae during normal activities such as walking, running,and bending of the spinal column. In other words, the implant strip maybe configured to endure axial loads that are usually applied to spinaldiscs. Additionally, the implant device may be configured to accommodatebending, lateral (including shear forces), and twisting forces.

FIGS. 11-14 are intended to illustrate a generic embodiment of implantdevice 2200. Generally, implant device 2200 may be any kind of deviceconfigured for implantation into the human body. In some cases, implantdevice 2200 may be configured to be implanted between vertebrae,functioning as a full or partial disc replacement device. In a preferredembodiment, implant device 2200 may be an implant strip.

FIG. 11 is intended to illustrate a general embodiment of implant device2200 in a pre-deflection state 2210 and a post-deflection state 2212. Inthis embodiment, implant device 2200 includes first portion 2202 andsecond portion 2204. Preferably, first portion 2202 is relatively rigidcompared to second portion 2204. In other words, second portion 2204 isconfigured to deflect under axial forces before first portion 2202 woulddeflect. As shown in FIG. 11, second portion 2204 has a first height H1in a pre-deflection state 2210 and a second height H2 in apost-deflection state 2212. First height H1 is preferably greater thansecond height H2. Additionally, first portion 2202 and second portion2204 have a third combined height H3, in pre-deflection state 2210 and afourth combined height H4 in post-deflection state 2212. Third combinedheight H3 is preferably greater that fourth combined height H4. Thispreferred arrangement allows for some deflection of implant device 2200without causing fatigue or failure.

In addition to deflection in the axial direction, a spinal implantdevice may also be configured to undergo bending, lateral and twistingmotions. Implant device 2200 is seen in FIG. 12 to undergo a bendingmotion due to bending forces 2209. As bending forces 2209 are applied tofirst portion 2202, second portion 2204 may bend. This preferredarrangement allows for some bending of implant device 2200 withoutcausing fatigue or failure.

Implant device 2200 is seen in FIG. 13 undergoing a lateral motion dueto a lateral force 2208. As lateral force 2208 is applied to firstportion 2202, second portion 2204 may be deflected laterally. Thispreferred arrangement allows for some lateral deflection of implantdevice 2200 without causing fatigue or failure.

Referring to FIG. 14, implant device 2200 is seen in undergoing atwisting motion due to a rotational force 2210. As rotational force 2210is applied to first portion 2202, second portion 2204 may be twisted.This preferred arrangement allows for some twisting of implant device2200 without causing fatigue or failure.

In each of these cases, first implant devices 2200 is provided withrestoring forces via second portion 2204. Additionally, although thesedifferent types of deflections (due to compressive, bending, twistingand lateral forces) have been shown separately, it should be understoodthat implant device 2200 may be configured to undergo any combination ofor all of these various types of deformations simultaneously.

First portion 2202 may be made of any material, including both shapememory alloys and spring steel, as well as other types of materials,including previously discussed materials for implant strip 1400. Secondportion 2204 may be made of any material that may be less rigid thanfirst portion 2202. In addition, second portion 2204 may be designed todeflect and/or deform under various forces. Examples of such materialsinclude, but are not limited to, elastomers, soft metals, plastics,polymers, wire meshes (made from materials such as Dacron or ceramics),as well as other types of materials.

Additionally, in some embodiments, first portion 2202 and second portion2204 could be made of the same material. However, the rigidity of secondportion 2204 could be modified by changing the structural properties ofsecond portion 2204. This configuration may be achieved by insertingholes or slots or modifying the structure of second portion 2204 inother ways. With these types of modifications, first portion 2202 may bemore rigid than second portion 2204 even though they are made of thesame material.

Preferably, the degree of deflection of implant device 2200 may vary.During the initial implantation, implant device 2200 may deflect orcompress until the height of the implant device is about eighty percentof the initial height of the implant strip prior to implantation. Thisinitial deflection is primarily due to normal stresses applied by theadjacent vertebrae when the spinal column is at rest. During motion,however, implant device 2200 may continue to deflect due to increasedaxial loads from the adjacent vertebrae. The degree of deflection may bebetween 15 and 25 percent of the initial height of implant device 2200.It should be understood, however, that the degree of deflection is notlimited and may vary according to properties of the various materialsthat are used. In some cases, the degree of deflection could be muchlarger than 25 percent or much less that 15 percent. By carefullyselecting the material, size, design as well as other structuralfeatures of second portion 2204, the deflection of implant device 2200can be better controlled. The following embodiments illustrate ways inwhich the deflection of implant device 2200 can be achieved usingdifferent materials and structural features for second portion 2204.

FIG. 15 is an isometric view of a preferred embodiment of implant strip2000. In some embodiments, implant strip 2000 may extend in a lateraldirection from a first lateral side portion 2002 to a second lateralside portion 2006. Preferably, first lateral side portion 2002 andsecond lateral side portion 2006 may be constructed of a similarmaterial to the implant strips of the previous embodiments. Inparticular, side portions 2002 and 2006 may be made of a substantiallyrigid material that does not deflect much under axial loads.

In some embodiments, elastomer strip 2004 may be disposed between firstlateral side portion 2002 and second lateral side portion 2006.Elastomer strip 2004 is preferably made of a flexible material. In someembodiments, elastomer strip 2004 may be joined to first lateral sideportion 2002 and second lateral side portion 2006. In some embodiments,elastomer strip 2004 may encase perforated edges, teeth or roughed edgesof first lateral side portion 2002 and second lateral side portion 2006in order to ensure a positive mechanical connection. In this preferredembodiment, first lateral side portion 2002 and second lateral sideportion 2206 may be associated with teeth 2007. Using thisconfiguration, teeth 2007 provide a point of attachment for elastomerstrip 2004 to first lateral side portion 2002 and second lateral sideportion 2006. In other embodiments, other provisions may be used tofixedly attach elastomer strip 2004 to first lateral side portion 2002and second lateral side portion 2006.

In some embodiments, implant strip 2000 may include a bone growthpromoting agent. In this embodiment, top portion 2003 and bottom portion2005 are preferably coated with a bone growth promoting agent 2001.Generally, any type of bone growth promoting agent may be used.Additionally, any type of pattern for a bone growth promoting agent maybe used. Various bone growth promoting agents and patterns have beenpreviously referenced. Using this configuration, implant strip 2000 maybe configured to stimulate increased bone growth at adjacent vertebraewhere implant strip 2000 is implanted. In some embodiments, such aconfiguration may be used in a manner similar to a spinal cage, whichprovides a means of fusing two vertebral bodies together.

FIGS. 16 and 17 are a preferred embodiment of implant strip 2000 afterit has been coiled. Initially, implant strip 2000 has an axial heightH5. As axial force 2012 is applied to flexible implant strip 2000,elastomer strip 2004 may deflect in the axial direction, allowing firstlateral side portion 2002 and a second lateral side portion 2006 tosqueeze together. In this embodiment, flexible implant strip 2000 has aheight H6 that is less than height H5 following axial deflection.Generally, elastomer strip 2004 has deformed and may slightly bulgeoutwards. This preferred arrangement allows implant strip 2000 todeflect under axial forces applied by adjacent vertebrae followingimplantation, which provides a similar function to a spinal disc. Also,using this configuration flexible implant strip 2000 may be configuredas a flexible spiral coil that may not escape containment. Preferably,using this arrangement, the adjacent vertebrae may engage lateral sideportions 2002 and 2006 of implant strip 2000 to lock it into place.

Referring to FIGS. 15-17, implant strip 2000 preferably is configured tobe coiled in a manner that prevents contact between adjacent coils. Inthis embodiment, implant strip 2000 may include first longitudinalportion 2080 and second longitudinal portion 2081 extending in alongitudinal direction down the length of implant strip 2000, as seen inFIG. 15. First longitudinal portion 2080 extends from first boundary2082 to second boundary 2083. Second longitudinal portion 2081 extendsfrom second boundary 2083 to third boundary 2084. Generally, the lengthsof each longitudinal portion 2080 and 2081 are approximately equal toone 360 degree turn of a coil when implant strip 2000 is in a coiledstate. In this embodiment, longitudinal portions 2080 and 2081 areadjacent to one another, however in other embodiments longitudinalportions 2080 and 2081 may not be adjacent to one another.

Preferably, first longitudinal portion 2080 is configured to form afirst inner coil 2086, as seen in FIGS. 15-17, as implant strip 2000forms a coiled shape. Likewise, second longitudinal portion 2081 isconfigured to form a second outer coil 2087. In a preferred embodiment,second outer coil 2087 is spaced radially outward from first inner coil2086. In some embodiments, first inner coil 2086 and second outer coil2087 are spaced apart by a radial distance R5 when first lateral sideportion 2002 and second lateral side portion 2006 are not in motion (seeFIG. 16). Generally, distance R5 may have any value and may vary fromone embodiment to another. Using this preferred arrangement, first innercoil 2086 and second outer coil 2087 are spaced to prevent contact withone another. Preferably, first inner coil 2086 and second outer coil2087 are also spaced apart when first lateral side portion 2002 andsecond lateral side portion 2006 are in motion, such as when implantstrip 2000 is in a compressed or axially deflected state (see FIG. 17).This arrangement helps to reduce or substantially eliminate particulatedebris that may result from the rubbing of various portions togetherover the lifetime of implant strip 1400.

Preferably, provisions for preventing contact between portions of animplant strip may be provided in other embodiments as well. Theprinciples discussed here may be generally applied to any type ofimplant strip including a first longitudinal portion and a secondlongitudinal portion. In some embodiments, these implant strips may ormay not include deforming portions.

In other embodiments, an implant strip may include different provisionsfor allowing deflection of the implant strip in the axial direction. Insome embodiments, an implant strip may include perforated portions withlarge gaps or holes that reduce rigidity and thereby allow for somedeflection of the implant strip. It should be understood that throughoutthese embodiments, illustrated in FIGS. 18-34, the various implantstrips include portions of differing rigidity. Furthermore, in each ofthese embodiments, the portions of differing rigidity are joinedtogether.

FIGS. 18-25 are preferred embodiments of sections of spinal implantstrips that are configured for various types of deflection, includingaxial deflection. The spinal implant strips are also capable ofaccommodating other types of deflection, including bending, twisting,and lateral shear. Throughout these embodiments, it should be understoodthat the implant strips may be made of any material configured to coilor deflect in the circumferential direction. In some embodiments, thesesections of implant strips may be made of a single material or comprisea combination of one or more materials including, but not limited to,cobalt chrome (CoCr), stainless steel, Nitinol, polymers, biologicalmatrices, ceramics or any biocompatible material. In a preferredembodiment, these sections of implant strips may be made of a materialincluding titanium.

FIG. 18 is a preferred embodiment of a portion of first implant strip2020 prior to deflection. First implant strip 2020 preferably includeslower edge 2002 and upper edge 2006. Lower edge 2002 and upper edge 2006are preferably thin strips that form an outer periphery for firstimplant strip 2020.

Additionally, first implant strip 2020 may include first deflectingportions 2024 that are disposed between lower edge 2002 and upper edge2006. Preferably, lower edge 2002 and upper edge 2006 are joined tofirst deflecting portions 2024. For purposes of clarity, only a sectionof first implant strip 2020 is shown here, however it should beunderstood that first deflecting portions 2024 are preferably disposedalong the entire length of first implant strip 2020. Generally, thespacing and number of first deflecting portions 2024 may be varied inorder to change the deflection properties of first implant strip 2020.

In this embodiment, first deflecting portions 2024 may be ellipticallyshaped prior to deflection. In other embodiments, the shape of firstdeflecting portions 2024 may vary. Examples of other shapes that may beused include, but are not limited to, circles, diamonds, as well as anypolygonal shape. Additionally, in other embodiments, the thicknessassociated with first deflecting portions 2024 could be changed. Byvarying these properties of first deflecting portions 2024, thedeflection properties of first implant strip 2020 may be modified.

In some embodiments, first implant strip 2020 may also include motionlimiting features that prevent excessive deflection in the axialdirection. In this embodiment, first implant strip 2020 may includemotion limiting tabs 2026. Preferably, motion limiting tabs 2026 may bedisposed between edges 2002 and 2006. Furthermore, motion limiting tabs2026 may be disposed within deflecting portions 2024 and/or adjacent todeflecting portions 2024.

Preferably, deflecting portions 2024 and motion limiting tabs 2026 maybe formed by cutting or removing portions of first implant strip 2020,which creates gaps within interior space 2022. This cutting may be doneusing techniques known in the art, such as stamping, punching, laserfusion and/or water drilling, or any combination of techniques. In otherembodiments, first implant strip 2020, including deflecting portions2024 and tabs 2026 may be formed using a die of some kind. Thesetechniques are preferably used to create smooth edges in order toprevent burrs. Using this configuration, scar tissue due to burrs may besubstantially reduced following implantation of first implant strip2020. In other embodiments, however, techniques used that leave burrsintact may be used so that the remaining burrs may facilitate in-growthof bone.

Following the insertion of first implant strip 2020 between two adjacentvertebrae, an axial force may be experienced as the vertebrae arecompressed during motion of the spinal column. Referring to FIG. 19,first deflecting portions 2024 may be compressed under axial force 2028.As first deflecting portions 2024 compress, lower edge 2002 and upperedge 2006 move closer together. As previously discussed, excessive axialdeflection may be prevented using motion limiting tabs 2026. Preferably,tabs 2026 are substantially rigid and therefore will not deflect ordeform under axial force 2028. Therefore, as tabs 2026 make contact, thecompression of first deflecting portions 2024 may cease. In thisembodiment, the height of implant strip 2020 has been modified from anoriginal height H3 to a modified height H4 that is less than H3. Onceaxial force 2028 has been removed or reduced, implant strip 2020 mayexpand in the axial direction as deflecting portions 2024 uncompress.Using tabs 2026 helps to prevent fatigue failure of deflecting portions2024 by limiting the range of motion.

Referring to FIGS. 20-25, an implant strip may include different typesof deflecting portions. Additionally, an implant strip may or may notinclude motion limiting tabs. In a second embodiment, seen in FIGS.20-21, second implant strip 2030 includes first deflecting ellipse 2032,second deflecting ellipse 2034 and third deflecting ellipse 2036disposed between edges 2002 and 2006 and within interior space 2038.Preferably, ellipses 2032, 2034, and 2036 are joined to edges 2002 and2006. As axial force 2028 is applied, deflecting ellipses 2032, 2034 and2036 are compressed until they obtain a substantially circular shape. Atthis point, ellipses 2032, 2034, and 2036 are disposed against oneanother, which may prevent any further deflection or deformation in theaxial direction.

In a third embodiment, shown in FIGS. 22-23, third implant strip 2040includes fourth deflecting ellipse 2042 and fifth deflecting ellipse2046 disposed between edges 2002 and 2006 and within interior space2048. Preferably, ellipses 2042 and 2046 are joined to edges 2002 and2006. In addition, third implant strip 2040 preferably includes crossbar 2044 that is disposed between fourth deflecting ellipse 2042 andfifth deflecting ellipse 2046. Cross bar 2044 preferably connects toboth lower edge 2002 and upper edge 2006. In a preferred embodiment,deflecting ellipses 2042 and 2046 as well as cross bar 2044 may alldeflect under axial force 2028. In particular, cross bar 2044 mayexperience column deflection. Preferably, cross bar 2044 only partiallydeflects, which limits the axial motion of lower edge 2002 and upperedge 2006.

In a fourth embodiment, seen in FIGS. 24-25, fourth implant strip 2050includes first curved portion 2052 and second curved portion 2056.Preferably, curved portions 2052 and 2056 are joined to edges 2002 and2006. Fourth implant strip 2050 also preferably includes motion limitingtabs 2054. As axial force 2028 is applied to fourth implant strip 2050,curved portions 2052 and 2056 may deflect in the axial direction.Preferably, as tabs 2054 make contact, the deflection of lower edge 2002towards upper edge 2006 may cease. Additionally, curved portions 2052and 2056 may contact edges 2002 and 2006, preventing further deflection.

FIGS. 26-28 illustrate another preferred embodiment of implant strip2300 that is configured for axial deflection. Implant strip 2300includes upper side 2304 and lower side 2306 that extend vertically.Protruding portion 2303 preferably extends outwards from, and ispreferably joined with, upper side 2304 and lower side 2306. Inparticular, protruding portion 2303 includes first sloped portion 2310and second sloped portion 2312 as well as flat portion 2308. Using thispreferred arrangement, implant strip 2300 may be configured for slightdeflections in the axial direction, as some slight compression ofimplant strip 2300 may occur at protruding portion 2303. In particular,as axial loads are applied to implant strip 2300, the angle of firstsloped portion 2310 and second sloped portion 2312 with respect to upperside 2304 and lower side 2306 may vary.

FIG. 28 illustrates an alternative embodiment of a cross sectional viewof protruding portion 2303. In the embodiment shown in FIG. 27, firstsloped portion 2310 and second sloped portion 2312 are straightportions. Alternatively, protruding portion 2303 could include firstcurved portion 2320 and second curved portion 2322. Using an alternativeshape for protruding portion 2303 allows for changes in the deflectingproperties of implant strip 2300. In other embodiments, the shape ofprotruding portion 2303 could be further modified to change thedeflecting properties of implant strip 2300.

Implant strip 2300 also preferably includes slots 2302. In thisembodiment, slots 2302 extend from upper side 2304 to lower side 2306 ofimplant strip 2300. Slots 2302 preferably extend through protrudingportion 2303. The addition of slots 2302 to implant strip 2300 generallydecreases the rigidity of protruding portion 2303. Using thisconfiguration, slots 2302 may provide increased deflection of protrudingportion 2303.

FIGS. 29 and 30 are a preferred embodiment of implant strip 2300following implantation. As implant strip 2300 is coiled, implant strip2300 is configured to deflect in the circumferential direction. In apreferred embodiment, the deflection primarily occurs at slots 2302.FIG. 30 illustrates the widening of slots 2302 during coiling. Forexample, first slot 2700 of implant strip 2300 is wider at first end2704 than second end 2702.

FIG. 31 is a preferred embodiment of outer ring 2332 of implant strip2300 undergoing axial deflection. For purposes of clarity, inner rings2330 of implant strip 2300 are shown in phantom. As an axial force isapplied, protruding portion 2303 deflects. In particular, the anglebetween upper side 2304 and first sloped portion 2310 and the anglebetween lower side 2306 and second sloped portion 2312 may change asupper side 2304 and lower side 2306 are squeezed together.

In some embodiments, the number, shape, and size of slots associatedwith an implant strip may vary. By changing the number, shape,orientation, and/or size of slots of an implant strip, the axial loadingcharacteristics of the implant strip may be controlled. Increasing thenumber of slots may increase the degree of axial deflection, as therigidity of protruding portion 2303 is reduced with an increasing numberof slots. Likewise, decreasing the number of slots may decrease thedegree of axial deflection, as the rigidity of protruding portion 2303is increased with a decreased number of slots.

Additionally, changing the number of slots may also increase theflexibility of the implant strip in the circumferential direction.Increasing the number of slots may generally increase the amount ofdeflection in the circumferential direction. Likewise, decreasing thenumber of slots may generally decrease the amount of deflection in thecircumferential direction.

FIG. 32 is a preferred embodiment of first implant strip 2800 and secondimplant strip 2804. First implant strip 2800 includes first slots 2802and second implant strip 2804 includes second slots 2806. Preferably,the number of slots comprising first slots 2802 is greater than thenumber of slots comprising second slots 2806.

Referring to FIG. 33, first implant strip 2800 and second implant strip2804 have different deflection characteristics since first implant strip2800 has a greater number of slots than second implant strip 2804. Inthis embodiment, first implant strip 2800 can deflect or curve more inthe circumferential direction than second implant strip 2804. Inparticular, first implant strip 2800 has a first radius of curvature R1than is smaller than a second radius of curvature R2 associated withsecond implant strip 2804.

By varying the radius of curvature of an implant strip in this manner,the tightness of coiling associated with an implant strip may be varied.Generally, a tighter coil provides more surface area over which toreceive axial loads from adjacent vertebrae and thereby increases thestrength of the implant strip in the axial direction.

In the previous embodiment, slots of different widths are used tomodifying the deflecting properties of an implant strip. In otherembodiments, the spacing between slots could vary. In still otherembodiments, the orientation of the slots may vary as well.Additionally, in some embodiments, the slots could have different shapessuch as oval, round, hexagonal or any type of polygon or irregularshape. These various shapes can be used singularly or in any desiredcombination.

In another embodiment, shown in FIG. 34, a portion of implant strip 3300includes a variety of punched out shapes configured to change thedeflecting characteristics of implant strip 3300. In some embodiments,implant strip 3300 may include thin slots 3302 and wide slots 3304. Inthis embodiment, the spacing between slots varies from spacing S1 tospacing S2. In this exemplary embodiment, spacing S1 is much larger thanspacing S2. In other embodiments, the spacing between slots could be anylength, and could vary over implant strip 3300.

In some cases, the orientation of slots could be modified. In someembodiments, implant strip 3300 may include angled slots 3310,Generally, angled slots 3310 may be oriented in any direction,including, in other embodiments, perpendicular to thin slots 3302.

Additional shapes for cutouts are also illustrated in FIG. 34. In someembodiments, implant strip 3300 may include circular cutouts 3312,triangular cutouts 3314, or diamond cutouts 3315. Furthermore, in somecases, the various shapes could be repeating or non-repeating, includingvarious geometric patterns such as honeycomb-like cutouts 3316. In thiscase, the remaining portions of implant strip 3300 may be configured aslattice 3318.

The various shapes and patterns illustrated in FIG. 34 are only meant tobe exemplary. In some embodiments, a single size, shape and spacing forcutouts or slots may be used. In other embodiments, a variety ofdifferent shapes for cutouts or slots including regular or irregularspacing between shapes may be used. By using slots or cutouts of varyingwidths, sizes, orientations and various spacing between slots orcutouts, the deflection properties and the coiling properties of implantstrip 3300 may be tuned.

Preferably, implant strips may be configured to permanently deflect insome situations. Generally, vertebrae are not completely symmetric andtherefore the spacing between two adjacent vertebrae may vary. Using animplant strip that is configured to partially permanently deflect atsome portions allows for a more natural fit of the implant strip.

FIG. 35 is a schematic view of a preferred embodiment of a portion ofspinal column 3100, including vertebrae 3102. Implant strip 3104 hasbeen inserted between vertebrae 3102 to replace a spinal disc. In thisembodiment, the spacing between vertebrae 3102 varies. In particular, atfront side 3106 of spinal column 3100, vertebrae 3102 are separated by aheight H7 while at rear side 3108 of spinal column 3100, vertebrae 3102are separated by a height H8 that is less than height H7. Preferably,implant strip 3104 has partially permanently deflected at rear side3108, allowing for a natural fit. It should be understood that implantstrip 3104 has only partially permanently deflected at rear side 3108.Generally, implant strip 3104 is configured to continue axial deflectionunder increased axial loads at front side 3106 and rear side 3108.

Using the configuration described here, the shape of implant strip 3104is preferably automatically customized. In some regions between adjacentvertebrae, such as the narrow region discussed above, the implant stripmay plastically deform to adjust to natural contours of the adjacentvertebrae. In other regions, such as the wider region discussed above,the implant strip may remain extended or minimally deflected to fullyfill in the spaces between vertebrae. In this manner, the implant strippreferably performs a similar function to a spinal disc.

Preferably, an implant strip may include provisions for facilitatingcoiling of the implant strip during implantation into a spine. In apreferred embodiment, a curved tube may be used to facilitate coiling ofan implant strip. The following embodiment is intended to illustrate aprovision for facilitating coiling of any type of implant strip. Itshould be understood that the following procedure may be used tofacilitate the implantation of any of the various implant stripsdiscussed earlier as well as other possible implant strips.

FIG. 36 is a preferred embodiment of implant strip 2110 being insertedinto cavity 1560 of intervertebral disc 1202. In this embodiment, theinsertion of implant strip 2110 is facilitated by delivery device 2102.Delivery device 2102 may be a catheter or similar tube configured forreceiving implant strip 2110. Preferably, distal end 2104 of deliverydevice 2102 is disposed just inside of cavity 1560 and includes curveddeforming tip 2106.

As implant strip 2110 is inserted, curved deforming tip 2106 helpsfacilitate some bending of implant strip 2110 in the circumferentialdirection. As insertion of implant strip 2110 continues, intermediateportion 2114 of implant strip 2110 is further coiled by inner curvedportion 2108 of delivery device 2102. This arrangement furtherfacilitates the coiling of distal end 2112 of implant strip 2110 towardsthe center of cavity 1560. Using delivery device 2102 allows forincreased control of coiling of implant strip 2110 during implantation.

In some embodiments, a spinal implant strip may be used to repair aherniated intervertebral disc. This may be achieved by using similartechniques for removing the herniated portion of the disc. Followingthis, a spinal implant strip may be inserted into the removed portion ofthe disc.

FIG. 37 is a plan view similar to that of FIG. 2, illustrating aherniated or traumatized intervertebral disc 1202. As shown, the nucleuspulposus 1224 is protruding from the intervertebral disc 1202 through acut or flaw 1204 in the intervertebral disc 1202. The protruding nucleuspulposus 1224 impinges on one of the exiting nerves 1218 as well as thespinal cord 1216 or cauda equina.

In cases where an intervertebral disc is herniated, such as is shownhere, portions of nucleus pulposus 1224 may be removed, as seen in FIG.38. This may be achieved using standard surgical techniques ortechniques similar to those discussed in the previous embodimentsillustrated in FIGS. 6-8. In some cases, a partial discectomy may bealso performed through a single tube or double tube. At this point,recess 3702 is left open within disc annulus 1222.

Preferably, implant strip 3802 may be inserted into recess 3702 torepair intervertebral disc 1202, as seen in FIG. 39. This may beaccomplished using similar techniques to those previously discussed forimplanting a spinal strip illustrated in FIGS. 6-8. As noted in theembodiment shown in FIGS. 6-8, implant strip 3802 may be inserted usinga single tube or double tube technique. Using this preferredarrangement, implant strip 3802 may be configured to replicate themechanical properties of nucleus 1224.

Using the various arrangements for a spinal implant strip discussed inthis detailed description provide for improved utility over priordesigns. Each of these designs is versatile since various types ofimplant strips may be used for replacing various kinds of spinal discs.Also, each of these arrangements provides for a single piece device thatdoes not experience the wear or generate particulate debris that may beassociated with multi-piece designs. Finally, using the materials anddesigns discussed in this detailed description, the implant strips arepreferably configured to either remain rigid or maintain a generalspring-like state without undergoing any fatigue or mechanical failure.

Embodiments of the present invention can provide for continuity of thespine. The term “continuity of the spine” generally refers to theconcept of providing an actual mechanical bridge between two distinctvertebral bodies. In some embodiments, this implant device provides fora mechanical bridge, while also allowing motion between the two distinctvertebral bodies. This arrangement can approximate the naturalbiomechanics of the spine.

By applying principles or features of the present invention, a surgeoncan implant a device to restore the original anatomical height of thedisk, thereby restoring normal forces across the spine. The surgeon canalso select an implant device that can provide decompression of thenerves in the vertebral foramen and canals. This implant device canprovide a post-implantation height greater than or less than theoriginal anatomical height of the disk. This implant device can alsoprovide a post-implantation configuration that optimizes the relativeposition between two vertebrae. In some cases, this post-implantationconfiguration can be used to correct scoliosis or spondylolisthesis.

In some embodiments, a spinal implant strip may include provisions forembedding into adjacent vertebrae. A spinal implant strip withprovisions for attaching to adjacent vertebrae may be useful in discreplacement procedures as well as disc fusion procedures. In otherembodiments, an implant strip may include teeth on a periphery of theimplant strip to assist in anchoring an implant strip to adjacentvertebrae. In some cases, teeth on a periphery of an implant strip mayfacilitate bone growth into the implant strip following implantation. Byincreasing the surface area on a periphery of an implant strip, teethmay facilitate bone growth into the implant strip.

FIGS. 40-43 are preferred embodiments of spinal implant strips withteeth disposed on a periphery of the implant strips. For the purpose ofclarity, the implant strips are illustrated schematically. Typically, animplant strip will have a much greater length than the implant stripsillustrated in these Figures. Preferably, the implant strips in theseembodiments may be inserted in an identical manner to the methods usedto insert the previously discussed implant strips of the previousembodiments.

Generally, teeth may be disposed on any portion of a periphery of animplant strip. In some embodiments, an implant strip may include teethon a lower edge. In some cases, teeth may be disposed on a portion of alower edge. In other cases, teeth may be disposed on an entirety of alower edge. In other embodiments, an implant strip may include teeth onan upper edge. In a preferred embodiment, an implant strip may includeteeth on an entirety of both a lower edge and an upper edge.Additionally, teeth may be disposed along an entirety of the length ofan implant strip, or just a portion of an implant strip. By usingdifferent configurations of teeth along an implant strip, an implantstrip can be embedded in various ways between two adjacent vertebrae.

Throughout the remainder of this detailed description and in the claims,the terms “upper edge” and “lower edge” generally refer to edges of animplant strip that extend in a longitudinal direction between a firstend and a second end of the strip. In particular, the upper edge isconfigured to contact a vertebrae disposed above a coiled implant strip,while the lower edge is configured to contact a vertebrae disposed belowa coiled implant strip.

FIGS. 40-41 illustrate an exemplary embodiment of implant strip 4000. Inthese embodiments, implant strip 4000 includes lower edge 4002 and upperedge 4006. Lower edge 4002 and upper edge 4006 form a portion of aperiphery of implant strip 4000. In this embodiment, lower edge 4002 andupper edge 4006 are configured with teeth 4010 disposed in a downwardand upward direction, respectively.

Typically, teeth may be configured in any shape and size. For example,in some cases, teeth may have an approximately symmetrical shape. Inother cases, teeth may have a saw tooth orientation. In still othercases, teeth may be rounded.

Various configurations of teeth may be included on an implant strip. Insome embodiments, teeth may conform to a repeating pattern. In somecases, for example, smaller teeth may be interspersed between largerteeth. In other embodiments, teeth may be identical in size and shape.In other embodiments, teeth may be disposed in different shapes andsizes on a periphery of an implant strip without a recognizable patternin an attempt to customize an implant strip to the anatomical shape ofvertebrae adjacent to the insertion site. In still other embodiments,teeth may be configured in multiple patterns on a periphery of animplant strip. For example, teeth disposed on an upper edge of animplant strip may be identical, while teeth disposed on a lower edge maybe a repeating pattern of smaller teeth interspersed between largerteeth.

In addition to teeth, embodiments of an implant strip may be configuredwith other provisions to encourage bone growth into the implant strip.These provisions may be applied to any desired portion of the implantstrip. Generally, in any of the embodiments discussed in this detaileddescription, a combination of macroscopic holes and microscopic holes orother bone growth promoting surface treatments can be used. By using acombination of both features, bone growth can be encouraged at thesurface of the implant strip so that the implant strip, on a surfacelevel, integrates with the bone; and by using macroscopic holes, largescale or bulk integration of the prosthesis can occur, furthersolidifying the integration of the implant strip with the bone. Detailsof these provisions can be found in U.S. Patent Publication Number US2009/0048675 (U.S. patent application Ser. No. 11/840,707, filed on Aug.17, 2007, entitled “Spinal Fusion Implants with Selectively Applied BoneGrowth Promoting Agent”), the entirety of which is incorporated byreference herein.

In the current embodiment, teeth 4010 are substantially identical withthe same size and shape. In particular, teeth 4010 are configured in asaw tooth orientation. Specifically, teeth 4010 extend height H9 frombase to apex. Furthermore, teeth 4010 are regularly spaced on edges 4002and 4006 and are separated by a distance D3 between apexes ofconsecutive teeth 4010. Generally, height H9 and distance D3 may haveany values and may vary from one embodiment to another. In thisembodiment, teeth 4010 are tightly spaced and distance D3 isapproximately the same as height H9 of teeth 4010.

FIG. 41 is an exemplary embodiment of implant strip 4000 after implantstrip 4000 has been coiled. In some embodiments, implant strip 4000 maybe pre-formed and coiled prior to implantation. Generally, any of theembodiments discussed in this detailed description may be coiled priorto implantation. For example, a surgeon may receive a preformed coiledimplant strip for implantation in some cases. For example, an implantstrip may be shaped into a preformed coil according to variousparticular features of a particular patient or the desires of thesurgeon. In other embodiments, as discussed previously implant strip4000 may coil as implant strip 4000 is implanted.

Upon implantation, teeth 4010 preferably extend upward and downward toengage adjacent vertebrae. Preferably, using this arrangement, teeth4010 facilitate the in-growth of bone from adjacent vertebrae. In thismanner, teeth 4010 may help embed implant strip 4000 into adjacentvertebrae.

Generally, teeth on a periphery of an implant strip may be regularly orirregularly spaced. In some embodiments, portions of a periphery mayinclude teeth that are regularly spaced, while other portions of aperiphery may include teeth that are irregularly spaced. In some cases,a surgeon may consider particular anatomical characteristics of a sitewhere an implant strip is to be inserted when choosing an implant stripwith regularly spaced or irregularly spaced teeth.

FIGS. 42 and 43 illustrate an exemplary embodiment of implant strip 4200with teeth 4210 spaced irregularly. In this embodiment, a periphery ofimplant strip 4200 includes lower edge 4202 and upper edge 4206. Teeth4210 are disposed on the entirety of both edges 4202 and 4206. In thisembodiment, teeth 4210 are configured with a rounded shape. Furthermore,the rounded shape of teeth 4210 includes a relatively low profile withan approximate height H10 at the apex. In some cases, the rounded shapeof teeth 4210 may prevent burrs and shorten the healing time after theimplantation of implant strip 4200.

While teeth 4210 include a rounded shape on edges 4202 and 4206, teeth4210 are not identical due to irregular spacing. For example, apexes ofconsecutive first tooth 4211 and second tooth 4212 disposed on upperedge 4206 are separated by distance D4. In contrast, apexes ofconsecutive third tooth 4213 and fourth tooth 4214 on lower edge 4202are separated by distance D5 that is less than distance D4. In thisembodiment, the spacing between teeth 4210 is irregular and variesbetween consecutive teeth.

FIG. 43 illustrates an exemplary embodiment of implant strip 4200coiled. In some cases, implant strip 4200 may be pre-formed prior toimplantation. In other cases, implant strip 4200 may coil as implantstrip 4200 is inserted. Preferably, teeth 4210 on lower edge 4202 andupper edge 4206 provide increased surface area to engage adjacentvertebrae and augment bone growth. Additionally, by spacing teeth 4210irregularly on a periphery of implant strip 4200, top surface 4306 andbottom surface 4406 may be configured to present a desired shape toadjacent vertebrae as implant strip 4200 is coiled. In some cases, teeth4210 may engage and provide support to adjacent vertebrae, while spacingbetween teeth 4210 may encourage the in-growth of bone and theattachment of implant strip 4200 to adjacent vertebrae.

Preferably, in the embodiments illustrated in FIGS. 40-43, teeth may beformed by cutting or removing portions of an implant strip. Cutting maybe done using techniques known in the art, including, but not limitedto, punching, laser fusion and/or water drilling, stamping, or anycombination of techniques. In other embodiments, teeth may be formedusing a die of some kind. Techniques are preferably used to createsmooth edges on the teeth in order to prevent burrs. With thisarrangement, scar tissue due to burrs may be substantially reducedfollowing the implantation of the implant strips. In still otherembodiments, however, techniques may be employed that leave burrs intactso that the remaining burrs facilitate in-growth of bone.

An implant strip may employ various provisions to prevent or limitcontact between adjacent coils when the implant strip is coiled. In somecases, increasing the space between adjacent coils may reduce orsubstantially eliminate rubbing that may create particulate debris. Inother cases, the creation of space between adjacent coils may enhancein-growth of bone into an implant strip. In still other cases, spacingof adjacent coils may allow a coiled implant strip to mimic the dynamicproperties of an intervertebral disc.

Generally, an implant strip may be configured to coil in a manner thatprevents or limits contact between all adjacent coils, a specific set ofadjacent coils, or a portion of the coil of adjacent coils. In someembodiments, a coiled implant strip may be configured to prevent contactbetween a first set of coils, but allow contact between a second set ofcoils. In other embodiments, adjacent coils may be configured to beseparated by a first distance on a first surface of an implant strip andseparated by a second distance, different from a first distance, on asecond surface of an implant strip. For example, in some cases, adjacentcoils may be spaced apart on a top surface of a coiled implant strip,but adjacent coils on a bottom surface may coil tightly without spacebetween adjacent coils. In a preferred embodiment, an implant strip mayinclude identical spacing between all adjacent coils.

FIGS. 44-49 are exemplary embodiments of implant strips with provisionsto prevent contact between adjacent coils. For the purpose of clarity,the implant strips in these embodiments are illustrated schematically.Typically, an implant strip will have a much greater length. Also, theimplant strips in these embodiments may be inserted in an identicalmanner to the methods used to insert the previously discussed implantstrips. In particular, the implant strips in these embodiments may coilduring implantation or as previously discussed, may be pre-formed into acoil for implantation. Furthermore, the implant strips in theseembodiments may include features discussed in any of the embodiments inthis detailed description.

Generally, an implant strip may include one or more separating portions.The term “separating portion” as used throughout this detaileddescription and in the claims refers to any provision for separatingadjacent coils of an implant strip. Separation portions may beconfigured on an implant strip in any manner known in the art. In someembodiments, separating portions may be integrally formed with animplant strip. In some cases, separating portions may be created bydeforming portions of an implant strip. For example, separating portionsmay be formed by forcing portions of a first surface upward to createprotrusions on an inner surface disposed opposite of the outer surface.Such a method of creating protrusions may also provide divots orrecesses on a second opposing surface. In other embodiments, separatingportions may be applied to an implant strip separately. In some cases,the separating portions could be integrally molded with the implantstrip. In other cases, the separating portions could be bonded orattached to the implant strip.

Referring to FIGS. 44-45, implant strip 4400 is configured withprotrusions 4410. Protrusions 4410 are disposed on inner surface 4420 ofimplant strip 4400. In particular, protrusions 4410 thrust outward frominner surface 4420. In this embodiment, protrusions 4410 aresubstantially similar and shaped as half spheres. In addition,protrusions 4410 are irregularly and rather widely spaced. Specifically,the spacing between protrusions 4410 is relatively greater than diameterD6 of protrusions 4410.

Generally, protrusions may have different shapes such as oval,hexagonal, rectangular, or any type of polygon or irregular shape. Thesevarious shapes can be used singularly or in any desired combination. Byusing different shapes, size and spacing, the deflection properties andthe coiling properties of an implant strip may be tuned. Typically, atighter coil provides more surface area over which to receive axialloads from adjacent vertebrae and thereby increases the strength of theimplant strip in the axial direction.

When implant strip 4400 is coiled, either prior to implantation orduring implantation, protrusions 4420 create spacing between adjacentcoils, as seen in FIG. 45. In particular, first inner coil 4501 andsecond outer coil 4502 are spaced apart by a radial distance R6.Generally, radial distance R6 may have any value and vary from oneembodiment to another. In this embodiment, radial distance R6 isapproximately equal to the height of protrusions 4410. Furthermore, whenimplant strip 4400 forms a coil, all coils of implant strip 4400 will beseparated by radial distance R6, since protrusions 4410 are identical.With this preferred arrangement, adjacent coils may not rub and createparticulate debris. In addition, due to the spacing between protrusions4410, bone from adjacent vertebrae may grow between adjacent coils tosecure implant strip 4400 in position.

In some embodiments, bone may be encouraged to grow between adjacentcoils by the application of a material. Generally, any type of materialmay be applied including, but not limited to polymers, polymers embeddedwith biological matrices, bone growth promoting agent, or anybiocompatible material. Furthermore, the material may be applied to anentirety or a portion of implant strip 4400 using any method known inthe art. In some cases, biological matrices, bone growth promotingagent, or another biocompatible material may be applied in a spongeapplication. Also, the bone growth promoting agent could be applied inas a paste in, for example, a “peanut butter” type application.

While this embodiment includes protrusions disposed on an inner surfaceof an implant strip, other embodiments may include protrusions or otherprovisions for spacing on an outer surface opposite of the innersurface. In some embodiments, provisions for spacing may be included onboth an outer and inner surface of an implant strip. Generally,protrusions or other provisions for spacing disposed on both surfaceswill increase the distance separating adjacent coils when an implantstrip is coiled.

FIGS. 46-49 illustrate an exemplary embodiment of implant strip 4600configured to coil in a manner that prevents contact between adjacentcoils. Preferably, implant strip 4600 includes inner surface 4620 andouter surface 4630 disposed opposite of inner surface 4620. In thisembodiment, material 4640 is applied to a portion of inner surface 4620and outer surface 4630, as seen in FIG. 47. In particular, material 4640is applied to cover regions on surfaces 4620 and 4630 between upperboundary 4606 and lower boundary 4602.

Generally, material 4640 may have any desired thickness to provide adesired separation between adjacent coils. In this embodiment, material4640 is applied with thickness T2. With this preferred arrangement,material 4640 creates space between adjacent coils when implant strip4600 is coiled.

Any type of material may be applied to an implant strip, including, butnot limited to, polymers embedded with biological matrices, bone growthpromoting agent, or any biocompatible material. In addition, thematerial may be applied to an implant strip in any manner known in theart. In some embodiments, the material may be applied in a pattern. Insome cases, the material could be applied in a regular pattern. In othercases, the material may be applied in an irregular pattern. Generally, amaterial may be applied with varying levels of thickness to any portionof an implant strip. In some embodiments, a material may be applied toproduce a particular spacing between adjacent coils of an implant strip.

Referring to FIG. 48, implant strip 4600 may be pre-formed and insertedor coiled during insertion. By applying material 4640 on both surfaces4620 and 4630, coils of implant strip 4600 may be spaced apart a radialdistance R7. Generally, radial distance R7 may be related to thicknessT2. In this embodiment, radial distance R7 is two times thickness T2,since material 4640 is applied to both surface 4620 and 4630 of implantstrip 4600. Using this preferred arrangement, adjacent coils of implantstrip 4600 are spaced to prevent contact with one another when implantstrip 4600 is formed into a coil.

Preferably, portions of implant strip 4600 extend above and below upperboundary 4606 and lower boundary 4602, respectively (see FIG. 46). Thisarrangement provides for the upper and lower edges of implant strip 4600to contact adjacent vertebrae directly. In particular, this arrangementmay facilitate implantation of implant strip 4600 into adjacentvertebrae. In some cases, the lower and upper edges may also be modifiedto include teeth or similar provisions for facilitating implantation.

Furthermore, since material 4640 is not applied to the entirety ofsurfaces 4620 and 4630, spaces or gaps may be created between adjacentradially spaced coils. In particular, portions of coiled implant strip4600 above upper boundary 4606 and below lower boundary 4602 may includespaces, as seen in FIGS. 48-49. This arrangement may spur bone growthbetween the coils of implant strip 4600. In other embodiments,boundaries 4606 and 4602 may be adjusted to alter the size of gaps orspaces between adjacent coils. This feature may be particularly usefulduring procedures involving disc fusion as well as disc replacement byengaging adjacent vertebrae and facilitating bone growth into implantstrip 4600.

Generally, a material may be used to help create separating portions forany type of implant strip. In the current embodiment, a material isapplied to a substantially flat implant strip. However, in otherembodiments, a material could be applied to other implant strips withdifferent shapes. In some embodiments, a material can be applied to animplant strip with provisions for deflecting and/or deforming to endurebending, lateral, axial, and twisting forces. In some cases, separatingportions may be applied to an implant strip to prevent the growth ofbone into portions of the coiled implant strip.

FIGS. 72-73 illustrate an exemplary embodiment of coiled implant strip7200. In this embodiment, implant strip 7200 is configured toaccommodate deflection in the axial direction. Preferably, implant strip7200 is substantially similar to implant strip 2300 as seen in FIGS.26-31. In particular, implant strip 7200 preferably includes protrudingportion 7203 (a portion of which is shown in FIG. 72 in phantom) thatextends outward from, and is preferably joined with, upper side 7205 andlower side 7201. With this arrangement, protruding portion 7203 maycompress under axial loads.

In addition, implant strip 7200 may be configured with material 7240that acts as a separating portion. In a similar manner to the previousembodiment, implant strip 7200 includes material 7240 that is applied toa portion of inner surface 7220 and outer surface 7230 of implant strip7200. Specifically, material 7240 is applied to cover regions of innersurface 7220 and outer surface 7230 between upper boundary 7206 andlower boundary 7202. Preferably, protruding portion 7203 is disposedbetween upper boundary 7206 and lower boundary 7202. In this manner,material 7240 may cover protruding portion 7203 and prevent the growthof bone into protruding portion 7203.

In some embodiments, material 7240 may alter the deflection propertiesof implant strip 7200 when material 7240 covers protruding portion 7203.In some cases, material 7240 may decrease the flexibility of protrudingportion 7203. In other embodiments, material 7240 may be configured withmaterial properties that do not interfere with the deflection propertiesof implant strip 7200.

Referring to FIG. 72, implant strip 7200 may be pre-formed in someembodiments. In other embodiments, implant strip 7200 may be coiledduring insertion. In this embodiment, coils of implant strip 7200 may bespaced apart by radial distance R10 by the application of material 7240on inner surface 7220 and outer surface 7230. Since material 7240 is notapplied to the entirety of inner surface 7220 and outer surface 7230,bone 7299 may grow into spaces between adjacent radially spaced coilsabove upper boundary 7206 and below lower boundary 7202. Thisarrangement preferably facilitates the attachment of implant strip 7200to bone.

Referring to FIG. 73, a cross section of coiled implant strip 7200 maybe clearly seen with protruding portion 7203 providing a flexible corefor implant strip 7200. With material 7240 applied to implant strip7200, the growth of bone 7299 between adjacent coils is blocked at upperboundary 7206 and lower boundary 7202. This arrangement prevents bone7299 from contacting protruding portion 7203 and interfering with thedeflection properties of protruding portion 7203.

Generally, the thickness of an implant strip will impact the diameter ofthe coiled implant strip. Typically, a thinner implant strip willrequire a greater length to achieve the same diameter when coiled as athicker implant strip. In other words, a thicker implant strip may havea shorter length but form a coiled shape with approximately the samediameter as a longer and thinner implant strip. In some cases, a thickerimplant strip with a shorter length may be preferable because it doesnot require as many coils to achieve a coiled shape with a particulardiameter. Furthermore, a thicker implant strip with a shorter length maybe easier to store than a thinner implant strip with a longer length.

The thickness of an implant strip may be increased in any manner knownin the art. In some embodiments, an implant strip may be constructedwith a greater thickness. In other embodiments, an implant strip may beconfigured with greater thickness by adding distinct portions to animplant strip. In some cases, multiple implant strips may be layeredtogether to create a single layered implant strip with an increasedthickness over a single implant strip. Preferably, every pair ofadjacent implant strips in a layered implant strip may be separated by aspacer portion.

FIGS. 66-68 illustrate an exemplary embodiment of dual implant strip6600. Although this embodiment is illustrated schematically, it shouldbe understood that dual implant strip 6600 is configured with length L5that is shorter than the typical length of thinner implant strips.Furthermore, dual implant strip 6600 is configured with thickness T6that is greater than the typical thickness of longer implant strips. Inorder to achieve greater thickness T6, dual implant strip 6600 isconfigured with layered implant strips.

In particular, dual implant strip 6600 is comprised of first implantstrip 6601 and second implant strip 6602. In this exemplary embodiment,first implant strip 6601 is configured with thickness T3. Likewise,second implant strip 6602 is configured with thickness T4. In addition,first implant strip 6601 includes inner surface 6611 and first centralsurface 6612 disposed opposite of inner surface 6611. In a similarmanner, second implant strip 6602 includes second central surface 6621and outer surface 6622 disposed opposite of second central surface 6621.

Generally, multiple implant strips may be joined in any manner to createa thicker implant strip. In some cases, multiple implant strips may beattached directly to each other. In other cases, multiple implant stripsmay be joined with another material disposed between the implant strips.

In this exemplary embodiment, dual implant strip 6600 includes spacerportion 6603. Spacer portion 6603 is disposed between first implantstrip 6601 and second implant strip 6602. Specifically, spacer portion6603 attaches to first central surface 6612 of first implant strip 6601.In a similar manner, spacer portion 6603 attaches to second centralsurface 6621 of second implant strip 6602. With this arrangement, dualimplant strip 6600 is configured with thickness T6 that is approximatelyequal to the sum of thickness T3, thickness T4 and thickness T5 ofspacer portion 6603.

Generally, spacer portion 6603 may be constructed of any materialdiscussed in this detailed description. In some cases, spacer portion6603 may be constructed of a flexible plastic to provide flexibility todual implant strip 6600. In other cases, spacer portion 6603 may beconstructed of shape memory alloy or shape-memory material to assistdual implant strip 6600 in coiling into a desirable shape followingimplantation.

Preferably, thickness T6 and length L5 of dual implant strip 6600 allowdual implant strip 6600 to form a coiled shape with fewer coils. FIG. 67is a schematic top down view of an exemplary embodiment of dual implantstrip 6600 formed in a coiled shape. Due to thickness T6 and length L5,dual implant strip 6600 forms two coils when shaped in a coil. Inparticular, dual implant strip 6600 is configured with first coil 6701and second coil 6702. For illustrative purposes, only two coils areshown here, however it should be understood that in other embodimentsdual implant strip 6600 may form additional coils as well.

Referring to FIG. 68, a cross section of coiled dual implant strip 6600may be clearly seen with spacer portion 6603 disposed between firstimplant strip 6601 and second implant strip 6602. By forming a coiledshape with fewer coils, dual implant strip 6600 may be easier to implantthan a longer thinner strip. Furthermore, the construction of dualimplant strip 6600 with spacer portion 6603, as well as first implantstrip 6601 and second implant strip 6602, provides opportunities tomanipulate the coiling properties of dual implant strip 6600.

In some cases, a dual implant strip may include provisions to facilitatebone growth into the implant strip. Generally, the growth of bone into adual implant strip may be encouraged in any manner known in the art. Insome embodiments, teeth may be disposed on edges of the dual implantstrip to facilitate bone growth into the dual implant strip. In otherembodiments, bone growth promoting agent may be applied to portions ofthe dual implant strip to assist bone growth into the dual implantstrip. In still other embodiments, a coiled dual implant strip may beconfigured with recesses or gaps so that bone may grow into the recessesand anchor the dual implant strip. In some cases, a dual implant stripmay be configured with a spacer portion and separating portions thatcreate space for the growth of bone into the coiled implant strip.

FIGS. 74-77 illustrate an exemplary embodiment of dual implant strip7400. As discussed in the previous embodiment, an implant strip may becomprised of multiple implant strips to create a single thicker implantstrip that requires fewer coils to achieve a coiled shape with aparticular diameter. In this embodiment, dual implant strip 7400comprises first implant strip 7401 and second implant strip 7402. Firstimplant strip 7401 and second implant strip 7402 may be configured withany width typical for an implant strip. In addition, first implant strip7401 includes inner surface 7411 and first central surface 7412 disposedopposite of inner surface 7411. Similarly, second implant strip 7402includes second central surface 7421 and outer surface 7422 disposedopposite of second central surface 7421.

Preferably, first implant strip 7401 is joined to second implant strip7402 by spacer portion 7403. Specifically, spacer portion 7403 attachesto a portion of first central surface 7412 of first implant strip 7401.Also, spacer portion 7403 attaches to a portion of second centralsurface 7421 of second implant strip 7402. In order to create space forthe growth of bone, spacer portion 7403 preferably extends from upperboundary 7492 to lower boundary 7491 on first implant strip 7401 andsecond implant strip 7402. In this manner, the upper and lower edges offirst implant strip 7401 and second implant strip 7402 may contactadjacent vertebrae directly.

Generally, an implant strip comprising multiple implant strips mayinclude separating portions. In some cases, an implant strip may beconfigured with separating portions to limit contact between adjacentcoils when the implant strip is coiled. In other cases, an implant stripmay include separating portions to create space between adjacent coilsto encourage bone growth into an implant strip.

In this embodiment, dual implant strip 7400 includes material 7451 thatacts as a separating portion. Material 7451 may be any material that mayserve as a separating portion discussed in previous embodiments.Preferably, material 7451 is applied to a portion of inner surface 7411of first implant strip 7401 and a portion of outer surface 7422 ofsecond implant strip 7402. In particular, material 7451 is applied tocover regions on inner surface 7411 and outer surface 7422 between upperboundary 7492 and lower boundary 7491. This arrangement creates spacefor the growth of bone above upper boundary 7492 and below lowerboundary 7491. In addition, this configuration leaves the upper andlower edges of first implant strip 7401 and second implant strip 7402free to contact adjacent vertebrae.

Spacer portion 7403 and material 7451 could be made of any material. Insome embodiments, spacer portion 7403 and material 7451 could be made ofsimilar materials. In other embodiments, spacer portion 7403 andmaterial 7451 could be made of different materials. In a preferredembodiment, spacer portion 7403 and material 7451 are both made of apolymer of some kind.

Generally, material 7451 may be applied with any thickness necessary toachieve the desired width of coiled implant strip 7400. In addition, thewidth of spacer portion 7403 may be greater or lesser than the width ofa typical implant strip. Preferably, adjusting the width of material7451 as well as adjusting the width of spacer portion 7403 may allow thediameter of the coiled dual implant strip 7400 to be fine tuned.

In some embodiments, dual implant strip 7400 may be pre-formed andinserted. In other embodiments, dual implant strip 7400 may coil duringimplantation. In a preferred embodiment, dual implant strip 7400 maycoil following insertion with a cannula. FIG. 75 illustrates a crosssectional view of an exemplary embodiment of cannula 7480 used forinserting dual implant strip 7400. Preferably, dual implant strip 7400can be inserted between adjacent vertebrae in a manner similar to theinsertion of a single implant strip. The details of this method havebeen previously discussed.

Referring to FIG. 76, dual implant strip 7400 is coiled followinginsertion. Due to the thickness of dual implant strip 7400, dual implantstrip 7400 conforms to a coiled shape that includes first coil 7691 andsecond coil 7692. In other embodiments, dual implant strip 7400 may beconfigured with more or less coils in a coiled shape. Furthermore, firstcoil 7691 and second coil 7692 are spaced a distance apart by material7451. Preferably, this spacing between first coil 7691 and second coil7692 prevents undesirable rubbing of adjacent coils.

FIG. 77 is a cross sectional view of the exemplary embodiment of coileddual implant strip 7400. Preferably, the creation of space within coileddual implant strip 7400 by spacer portion 7403 and material 7451 allowsbone 7499 to grow into dual implant strip 7400. In particular, bone 7499grows between first implant strip 7401 and second implant strip 7402into the spaces created by spacer portion 7403. Additionally, bone 7499grows into adjacent coils of coiled dual implant strip 7400.Specifically, bone 7499 grows into spaces created between first coil7691 and second coil 7692 by material 7451. Furthermore, bone 7499 isblocked from growing between upper boundary 7492 and lower boundary 7491of dual implant strip 7400 by spacer portion 7403 and material 7451.With this arrangement, the upper and lower edges of first implant strip7401 and second implant strip 7402 are free to contact adjacentvertebrae. This configuration allows dual implant strip 7400 to beanchored into place between adjacent vertebrae.

As previously discussed, an implant strip may be configured withdistinct portions that are made of different materials. Differentmaterials may have different material properties, including deflectionand/or deformation properties. By constructing distinct portions of animplant strip with different materials, the deflection and/ordeformation properties of an implant strip may be fine tuned.

FIG. 69 illustrates an exemplary embodiment of implant strip 6900. Inthis embodiment, implant strip 6900 is comprised of first portion 6901and second portion 6902. First portion 6901 is constructed of a firstmaterial. Similarly, second portion 6902 is constructed of a secondmaterial. In this case, the first material and second material aredifferent materials. Furthermore, the first material and second materialhave different deflection and/or deformation properties. Generally, thefirst material and second material may be any type of discussed in thisdetailed description. In this exemplary embodiment, the first materialis a more elastic material and the second material is a more rigidmaterial.

Generally, distinct portions may be disposed in various configurationsto create an implant strip. In this exemplary embodiment, first portion6901, constructed of the more elastic first material, includes firstregion 6931 and second region 6932. First region 6931 and second region6932 extend in a longitudinal direction between first end 6951 andsecond end 6952 of implant strip 6900. In particular, first region 6931is disposed near upper edge 6920. In a similar manner, second region6932 is disposed near lower edge 6910.

Second portion 6902 includes central region 6961 as well as upper edge6920 and lower edge 6910. This provides implant strip 6900 with rigidcentral region 6961 as well as rigid upper edge 6920 and rigid loweredge 6910. Additionally, flexible first region 6931 and flexible secondregion 6932 are interspersed between central region 6961, upper edge6920 and lower edge 6910. In this manner, implant strip 6900 may deformnear upper edge 6920 and lower edge 6910 although upper edge 6920 andlower edge 6910 maintain a rigid shape. In some cases, thisconfiguration may increase the strength of implant strip 6900 in theaxial direction. Furthermore, this arrangement may assist implant strip6900 in enduring bending, lateral, and twisting forces.

By selecting materials with particular deflection and/or deformationproperties and incorporating those materials into distinct portions ofan implant strip, the deflection and/or deformation characteristics ofan implant strip may be fine tuned. For example, in an alternativeembodiment of implant strip 6900, the second material may be moreflexible than the first material. In other words, upper edge 6920 andlower edge 6910 as well as central region 6961 may be constructed of aflexible material while first region 6931 and second region 6932 areconstructed of a more rigid material. In some cases, the flexiblematerial may allow upper edge 6920 and lower edge 6910 to deform withcontact from adjacent vertebrae. However, the rigid material of firstregion 6931 and second region 6932 may limit the deflection and/ordeformation. Also, central region 6961 may defect and/or deform toendure bending, lateral, axial, and twisting forces. Preferably, thedeflection and/or deformation properties of an implant strip may betuned by altering the materials as well as the sizes and shapes ofdistinct portions of an implant strip.

Distinct portions of an implant strip may be attached in various mannersto create the implant strip. In embodiments where distinct portionscomprising materials of differing flexibility are used, theseembodiments can include provisions for facilitating attachment betweenthe distinct portions. Preferably, these embodiments can includeprovisions to help prevent the distinct portions from detaching overtime and with use.

FIGS. 70-71 illustrate an exemplary embodiment of a portion of implantstrip 7000. In this embodiment, implant strip 7000 includes threedistinct portions. In particular, implant strip 7000 includes upperportion 7002, lower portion 7001 and central portion 7003. Upper portion7002 preferably includes upper edge 7020 of implant strip 7000. Inaddition, upper portion 7002 includes first bottom edge 7021. In asimilar manner, lower portion 7001 preferably includes lower edge 7010and first top edge 7011. Furthermore, central portion 7003 extends fromsecond top edge 7052 to second bottom edge 7051. In a preferredembodiment, central portion 7003 may overlap with first bottom edge 7021of upper portion 7002 and first top edge 7011 of lower portion 7001.

In different embodiments, the shape of first top edge 7011 and firstbottom edge 7021 may vary. In some embodiments, first bottom edge 7021and first top edge 7011 may have a wave like shape. In otherembodiments, first bottom edge 7021 and first top edge 7011 could begenerally straight. In this preferred embodiment, first bottom edge 7021and first top edge 7011 have a wave like shape that varies in a periodicmanner. This arrangement may provide periodically spaced portions thatcan facilitate attachment of upper portion 7002, lower portion 2001 andcentral portion 7003.

Generally, upper portion 7002, central portion 7003, and lower portion7001 may be constructed from any material discussed in this detaileddiscussion. In this exemplary embodiment, upper portion 7002 and lowerportion 7001 are constructed of a relatively rigid material.Additionally, central portion 7003 is configured of a relatively moreelastic material. This configuration preferably allows implant strip7000 to deform and endure axial loads from adjacent vertebrae.

Preferably, upper portion 7002 and lower portion 7001 include provisionsto attach to central portion 7003. In this exemplary embodiment, upperportion 7002 and lower portion 7001 include gaps 7050. Gaps 7050 aredisposed at intervals proximate to both first bottom edge 7021 and firsttop edge 7011. In particular, gaps 7050 may be associated with crests offirst bottom edge 7021 and first top edge 7011. Although only a portionof implant strip 7000 is illustrated in FIG. 70, it may be assumed thatgaps 7050 extend at intervals in a longitudinal direction between afirst end and a second end of implant strip 7000.

Referring to FIG. 71, gaps 7050 extend from inner surface 7081 of upperportion 7002 and lower portion 7001 to outer surface 7082 of upperportion 7002 and lower portion 7001. Preferably, central portion 7003may be configured to extend through gaps 7050 within upper portion 7002and lower portion 7001. With this arrangement, portions of upper portion7002 and lower portion 7001 may be embedded within central portion 7003.This configuration can assist in securely attaching central portion 7003to upper portion 7002 and lower portion 7001.

Central portion 7003 also preferably extends between first bottom edge7021 and first top edge 7011. As seen in FIG. 71, in a preferredembodiment, central portion 7003 may comprise a generally monolithicelastic material. This generally monolithic arrangement may provideincreased structural stability for implant strip 7000. In otherembodiments, however, central portion 7003 could include any number ofholes, gaps, voids, and/or channels. In some cases, holes, gaps, voidsand/or channels can be used to modify the overall elastic properties ofcentral portion 7003.

The preferred arrangement illustrated in FIGS. 70 and 71 may help toprevent separation between portions comprising distinct materials. Inparticular, upper portion 7002 is prevented from separating from centralportion 7003 since central portion 7003 is disposed through gaps 7050 inupper portion 7002. Likewise, lower portion 7001 is prevented fromseparating from central portion 7003 since central portion 7003 isdisposed through gaps 7050 in lower portion 7001. By substantiallyreducing the likelihood that distinct portions of implant strip 7000 mayseparate, the lifetime of implant strip 7000 can be substantiallyincreased.

Generally, an implant strip may be configured to coil into anyparticular shape. In some embodiments, a coiled shape of an implantstrip may be tailored to the replacement of an intervertebral disc orvertebral body of a patient. In some cases, an implant strip may beconfigured to coil into a particular shape to partially or fully fill acavity of an intervertebral disc and provide increased support to theadjacent vertebrae. In other cases, an implant strip may conform to aparticular coiled shape to replace a vertebral body. In otherembodiments, a coiled implant strip may be configured to a particularshape to increase the effectiveness of a disc fusion procedure. In stillother embodiments, an implant strip may be designed with a particularcoiled shape to accommodate the insertion of multiple implant strips.

FIGS. 50-53 illustrate exemplary embodiments of implant stripsconfigured to coil into a particular shape. These embodiments are notmeant to be limiting, in other embodiments, implant strips may beconfigured to coil into additional coiled shapes. Preferably, theimplant strips in these embodiments may be inserted in an identicalmanner to the methods used to insert the previously discussed implantstrips. In particular, the implant strips in these embodiments may bepre-formed and inserted (see FIGS. 51 and 53) or may coil duringinsertion (see FIGS. 50 and 52). Additionally, delivery devices mayassist in the insertion and configuration of the implant strips intoparticular coiled shapes. Furthermore, the implant strips in theseembodiments may include all the features discussed in the previous andfollowing embodiments.

Generally, the implant strips in these embodiments may be made of anymaterial, including shape memory alloys and spring steel, as well asother types of materials, including materials discussed in otherembodiments. An implant strip may be constructed from any suitablematerial that may be configured to assume a desired shape when formed ina coil.

In some embodiments, the shape of a coiled implant strip may bemodified. In previous embodiments, the implant strips retain a generallycylindrical shape. In other embodiments, however, it may be desirable tomodify the shape of the implant strip to adjust various loadingproperties of the coil. For example, using a kidney shaped coil mayallow the surgeon to modify the axial loading properties along variousportions between two adjacent vertebrae.

Referring to FIG. 50, implant strip 5000 may be configured to coil intoa kidney shape. In this schematic illustration of the coiling of implantstrip 5000, distal end 5001 of implant strip 5000 preferably forms firstcurved portion 5003 and second curved portion 5004 to create a kidneyshaped first inner coil 5005. By following first inner coil 5005, theremainder of implant strip 5000 may be configured to coil into a kidneyshape.

When coiled in the kidney shape, implant strip 5000 has width W2 andlength L2, as seen in FIG. 51. In this embodiment, length L2 issignificantly greater than width W2. Generally, length L2 and width W2may have any value and vary from one embodiment to another.

Furthermore, the kidney shape of coiled implant strip 5000 producesdifferent radial distances between different portions of adjacent coils.In some cases, adjacent coils may be separated by greater distances onportions of coils disposed along the longitudinal axis of implant strip5000 and separated by shorter distances on portions of the coilsdisposed along the latitudinal axis. For example, first outer coil 5101and second outer coil 5102 may be separated by radial distance R8 atfirst portion 5110, disposed along the longitudinal axis of implantstrip 5000. At second portion 5111, disposed along the latitudinal axisof implant strip 5000, first outer coil 5101 and second outer coil 5102are separated by radial distance R9 that is less than radial distanceR8. In general, the coiled shape of an implant strip may produce variousspacing between portions of adjacent vertebrae. With this preferredarrangement, the in-growth of bone may be encouraged at particularportions of implant strip 5000.

As previously discussed, multiple implant strips may be implantedsimultaneously between adjacent vertebrae. In some cases, by modifyingthe shapes of one or more implant strips, a surgeon may implant multipleimplant strips between adjacent vertebrae in different arrangements.

Implant strip 5000 may be implanted with second implant strip 5100, asseen in FIG. 51. In this embodiment, second implant strip 5100 isidentical in size and shape to implant strip 5000. However, secondimplant strip 5100 is oriented as a mirror image of implant strip 5000.In other embodiments, any number of implant strips configured withvarious coiled shapes and oriented in a variety of directions may beimplanted with implant strip 5000. In some cases, each implant strip maybe associated with a different height to create Lordosis or correctscoliosis. Preferably, multiple implant strips may be inserted to fill adisc region and provide support to adjacent vertebrae.

FIGS. 52-53 illustrate a schematic view of an exemplary embodiment ofimplant strip 5200. In this embodiment, implant strip 5200 is configuredto coil in an oval shape. In particular, first distal end 5201introduces first curved portion 5203 and second curved portion 5204 tocreate first inner coil 5205. Preferably, by following first inner coil5205, the remainder of implant strip 5200 may be configured to coil intoan oval shape.

FIG. 53 illustrates a schematic view of an exemplary embodiment ofcoiled implant strip 5200 implanted with second implant strip 5300.Preferably, implant strips 5200 and 5300 are coiled in identical ovalshapes. In particular, implant strip 5200 has length L4 and width W4that is less then length L4. In a similar manner, second implant strip5300 has length L3 and width W3. Lengths L3 and L4, as well as widths W3and W4, are substantially identical in this embodiment. Generally,lengths L3 and L4, as well as widths W3 and W4, may have any value andvary from one embodiment to another. In this embodiment, the oval shapeof implant strips 5200 and 5300 produces approximately similar radialdistances between adjacent coils.

Additionally, in this embodiment, implant strips 5200 and 5300 areinserted in opposite orientations. Specifically, implant strips 5200 and5300 are inserted so that second end 5202 of implant strip 5200 andsecond end 5302 of second implant strip 5300 are disposed opposite ofeach other. Preferably, the insertion of implant strips 5200 and 5300provides spinal continuity.

Typically, vertebrae are not completely symmetric and so the spacingbetween adjacent vertebrae may vary. A coiled implant strip thatpresents a particular shape at the top and/or bottom surface of theimplant strip may allow for a more natural fit of the implant stripbetween adjacent vertebrae. In particular, an implant strip thatpresents different portions with differing axial heights can provide fora better fit between a coiled implant strip and adjacent vertebrae. Withthis arrangement, an implant strip may fit the natural contours of theadjacent vertebrae and perform a similar function to a spinal disc.

In some embodiments, a coiled implant strip may provide a particularcontour on a top surface, while presenting a flat profile on a bottomsurface. In other embodiments, a coiled implant strip may provide aparticular contour on a bottom surface, although a top surface of thecoiled implant strip is generally flat. In still other embodiments, acoiled implant strip may provide a first contour on a top surface and asecond contour, different from the first contour, on a bottom surface.In a preferred embodiment, an implant strip may include symmetricalsurfaces on a top and bottom surface when coiled.

Preferably, in these embodiments, contours of a top and/or bottomsurface of a coiled implant strip may be formed by shaping a top and/orbottom edge of an implant strip. The shape of a top and bottom edge ofan implant strip may be created by cutting or removing portions of animplant strip. Cutting may be done using techniques known in the art,including, but not limited to, punching, laser fusion and/or waterdrilling, stamping, or any combination of techniques. In otherembodiments, a shape on an edge may be formed using a die of some kind.

FIGS. 54-62 illustrate schematic views of exemplary embodiments ofimplant strips that present particular contours on the top and bottomsurfaces of the implant strips when coiled. For the purpose of clarity,the implant strips in these embodiments are illustrated schematicallyand are typically much longer. Preferably, the implant strips in theseembodiments may be inserted in an identical manner to the methods usedto insert the previously discussed implant strips. In some cases, theimplant strips in these embodiments may be pre-formed prior toinsertion. In other cases, the implant strips in these embodiments maycoil during insertion. Also, the implant strips in these embodiments mayinclude any other features discussed in other embodiments in thisdetailed description.

FIGS. 54-56 illustrate an exemplary embodiment of implant strip 5400.Implant strip 5400 includes upper edge 5406 and lower edge 5402. In thisembodiment, upper edge 5406 and lower edge 5402 are configured with asymmetrical curvilinear shape, including interspersed crests andtroughs. Specifically, the shape on edges 5406 and 5402 is configured toprovide implant strip 5400 with maximum height H12 at first crest 5411disposed on upper edge 5406 and corresponding second crest 5412 disposedon lower edge 5402. In addition, implant strip 5400 is configured withminimum height H11 at first trough 5421 disposed on upper edge 5406 andcorresponding second trough 5422 disposed on lower edge 5402.Furthermore, the crests and troughs on edges 5406 and 5402 conferintervening heights between maximum height H12 and minimum height H11 onimplant strip 5400. In particular, successive crests on edges 5406 and5402 are separated by a distance approximately equal to one 360 degreeturn of a coil when implant strip 5400 is in a coiled state. In asimilar manner, successive troughs on edges 5406 and 5402 are separatedby a distance approximately equal to one 360 degree turn of a coil whenimplant strip 5400 is in a coiled state.

When implant strip 5400 is coiled, the curvilinear shape on edges 5406and 5402 preferably creates a wedge shape, as seen in FIG. 55. Inparticular, coiled implant strip 5400 has maximum height H12 at firstportion 5501 and minimum height H11 at second portion 5502. With thispreferred arrangement, upper edge 5406 creates an inclined plane on topsurface 5506. In a similar manner, lower edge 5402 provides an inclinedplane on bottom surface 5590. FIG. 56 is a cross sectional view of theexemplary embodiment of implant strip 5400 in a coiled state.

In some cases, a wedge shaped implant strip may be used to correctscoliosis or spondylolisthesis. In other cases, a wedge shaped implantstrip may assist in providing lordosis to a vertebral column. Inparticular, in some embodiments, a coiled implant strip with a wedgeshape may be inserted to orient a portion of the coiled implant stripwith a maximum height to the anterior and a portion of the coiledimplant strip with a minimum height to the posterior of a patient. Inother embodiments, the orientation of an implanted wedge shaped coiledimplant strip may be tailored to a specific patient. For example, awedge shaped coiled implant strip may be oriented to correct scoliosisin a patient.

In some embodiments, an implant strip may be tapered to create a concaveshape on a top and/or bottom surface when the implant strip is coiled.FIGS. 57-59 illustrate an exemplary embodiment of implant strip 5700tapered from second end 5702 to first end 5701. In particular, secondend 5702 extends maximum height H14 and first end 5701 extends minimumheight H13. Generally, maximum height H14 and minimum height H13 mayhave any values and may vary from one embodiment to another. Inaddition, in the current embodiment upper edge 5716 and lower edge 5712smoothly decline from second end 5702 to first end 5701. In otherembodiments, edges 5716 and 5712 may decline in another manner.

Referring to FIG. 58, implant strip 5700 is coiled with first end 5701disposed on an inner coil. Second end 5702 is disposed on outer coil5810. With this arrangement, coiled implant strip 5700 presents agenerally concave shape on top surface 5806. Likewise, a generallyconcave shape is disposed on bottom surface 5802. FIG. 59 provides across sectional view of the exemplary embodiment of implant strip 5700.Minimum height H13 may be clearly seen at the center of coiled implantstrip 5700 in this Figure. Using this configuration, adjacent vertebraemay be supported and in-growth of bone into implant strip 5700 mayassist in anchoring implant strip 5700 in position.

In other embodiments, an implant strip may be configured to create aconvex shape on a top and/or bottom surface of the coiled implant strip.FIGS. 60-62 illustrate an exemplary embodiment of implant strip 6000,including first end 6001 and second end 6002. In this embodiment,implant strip 6000 is tapered with upper edge 6016 and lower edge 6012smoothly declining from first end 6001 to second end 6002. Inparticular, first end 6001 is configured with maximum height H15. In asimilar manner, second end 6002 is configured with minimum height H16.Generally, maximum height H15 and minimum height H16 may have any valuesand may vary from one embodiment to another.

With this arrangement, implant strip 6000 is coiled with first end 6001disposed at the center of the coiling, as seen in FIG. 61. Also, secondend 6002 is disposed on outer coil 6010. Preferably, upper edge 6016 ofcoiled implant strip 5700 creates a generally convex shape on topsurface 6106. Likewise, lower edge 6012 creates a generally convexshaped on bottom surface 6102. A cross sectional view of the exemplaryembodiment of implant strip 6000 is illustrated in FIG. 62. The convexshape on top surface 6106 and bottom surface 6102 with maximum heightH15 disposed at the center of the coiling of implant strip 6000 may beclearly seen in this Figure. This preferred arrangement may providespinal continuity and encourage bone growth, in particular, on aperiphery of coiled implant strip 6000.

Preferably, the different provisions of implant strips discussed in thisdetailed description may be combined to create a spinal implant stripthat maximizes the utility of the implant strip for a particularpatient. Furthermore, a bone growth promoting agent may be applied to aportion or an entirety of an implant strip in concert with any otherprovisions described in this detailed description. Generally, a surgeonor medical expert may assess a patient and configure a spinal implantdevice based on factors specific to the patient. In some cases, forexample, a surgeon or medical expert may consider the location of thedamaged tissue, size of the vertebrae, and anatomical shape of thevertebrae or spinal disc as factors in the design choice of an implantstrip. In other cases, a particular combination of provisions of animplant strip may be chosen to correct scoliosis or spondylolisthesis.In still other cases, an implant strip may be configured to alleviatecompression of the nerves in the spinal foramen and canal. Generally, animplant strip may be configured with particular provisions toapproximate the natural biomechanics of the spine and provide for spinalcontinuity.

FIGS. 63-65 illustrate a schematic representation of an embodiment ofvarious provisions associated with implant strips and exemplarycombinations of those various provisions to create implant strips. Inthis embodiment, these provisions are arranged into various provisionsets, grouped with common properties. In other embodiments, theseprovisions may be arranged differently. In this embodiment, a first rowincludes teeth set 6301 with a choice of teeth disposed on an upper andlower edge of an implant strip. Additionally, a second row containsspacing set 6302 with a choice of spacing features that may be disposedon an implant strip. In a similar manner, a third row containsdeflection set 6303 with provisions for the deflection of an implantstrip. Also, a fourth row includes shape set 6304 that includes variousshapes configured on the top and bottom surfaces of implant strips.

Furthermore, the first choice in each set 6301-6304, notably firstcolumn 6311, provides the option for not selecting the featureassociated set. For example, first implant strip 6321 of teeth set 6301has no teeth on an upper or lower edge. However, second implant strip6322 of teeth set 6301 includes teeth disposed in a saw tooth pattern onan upper edge and lower edge. Teeth set 6301 further includes thirdimplant strip 6323 with irregularly spaced rounded teeth disposed on anupper and lower edge. In some embodiments, additional elements withother provisions may be added to sets 6301-6304. In some cases, forexample, an implant strip with regularly spaced rounded teeth disposedon an upper edge may be added to teeth set 6301. Also, in otherembodiments, additional sets with other provisions may be consideredwhen selecting features for an implant strip tailored for a particularpatient.

FIG. 63 illustrates a schematic view of an exemplary embodiment of aselection of provisions for implant strip 6350. In this embodiment, asaw tooth pattern for teeth is selected from second implant strip 6322of teeth set 6301. Additionally, first option 6350 with no spacing ischosen from spacing set 6302. Also, second option 6352 of an implantstrip with provisions for axial deflection is selected from deflectionset 6303. Finally, wedge shape 6354 is chosen from shape set 6304. Withthis combination of features, implant strip 6356 is created andpreferably tailored to different properties of a deformation of a spineof a particular patient.

FIG. 64 illustrates a schematic view of the selection of features for asecond exemplary embodiment of spinal implant strip 6450. In thisembodiment, first option 6321 with no teeth disposed on an upper andlower edge from teeth set 6301 is selected. Next, protrusion option 6452is chosen as spacers from spacing set 6302. In a third choice, anelastomer strip option 6354 is selected from deflection set 6303. In afourth choice, convex shape option 5356 with a convex top and bottomsurface is chosen from shape set 6304. With this combination ofselections, implant strip 6450 may be constructed and preferably betailored to conditions in a spine of a specific patient.

FIG. 65 illustrates a schematic view of the combination of features fora third exemplary embodiment of spinal implant strip 6550. In thisembodiment, saw tooth option 6322 for teeth is selected from teeth set6301. In a second choice, no spacing provisions are selected fromspacing set 6302. Additionally, no deflection provisions are selectedfrom deflection set 6303. Finally, no modified shape provisions arechosen from shape set 6304. This combination of provisions yieldsimplant strip 6550. With this preferred arrangement, implant strip 6550includes features to embed into adjacent vertebrae following insertion.

In addition to the combinations of implant strips that have already beendescribed, it is also possible to form other combinations. If there arethree distinct elements in a teeth set, three distinct elements in aspacing set, four distinct elements in a deflection set, and fourdistinct elements in a shape set, then there are one hundred andforty-four distinct implant strips that can be formed. As the number ofdistinct feature sets and the number of elements within feature setsincreases, the total number of possible implant strips grows. A largernumber of distinctly configured implant strips allows a medical expertor surgeon to make more subtle adjustments to an implant disc toincrease the ability of an implant strip to mimic the dynamic propertiesof a disc and/or provide for the continuity of a spine.

As discussed previously, an implant strip may include provisions tochange shape. In some embodiments, an implant strip with provisions tochange shape may be constructed of a shape-memory material. An implantstrip constructed of a shape-memory material may be configured in afirst shape prior to implantation. After implantation, the implant stripmay assume a second shape that is different from the first shape.

In some cases, a signal associated with implantation may trigger theimplant strip to transform to the second shape. Generally, the signalassociated with implantation may be any type of signal including, butnot limited to, heat, light, a local chemical environment, or mechanicalor electrical stimulation. For example, when an implant strip isimplanted, the body temperature of a patient may trigger the implantstrip to transform into a second shape.

Generally, an implant strip constructed of shape-memory material mayform various types of second shapes following implantation. In somecases, the second shape may be an oval shape. In other cases, the secondshape may be any desired shape, including a circular shape or a kidneyshape. Preferably, incisions to implant an implant strip constructed ofshape-memory material may be smaller because the implant strip mayassume a second shape without assistance from a surgeon.

It is also possible that an implant strip constructed of a shape-memorymaterial may expand in size following implantation. Preferably, this mayallow an implant strip to be constructed with a smaller size thannecessary. With this arrangement, an implant strip may be constructedwith a first size. Following implantation, the implant strip may expandto a second size that is larger than the first size. In this manner,smaller incisions may be made to implant the implant strip. This canprovide reduced trauma and faster healing rates following implantationof an implant strip constructed of shape-memory material.

While various embodiments of the invention have been described, thedescription is intended to be exemplary, rather than limiting, and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the invention. Accordingly, the invention is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

What is claimed is:
 1. A spinal prosthesis comprising: an implant stripmade of metal and configured for insertion between a first vertebra anda second vertebra, wherein the implant strip forms a first inner coiland a second outer coil that coils around the first inner coil, whereinthe implant strip includes a lateral dimension extending from a firstlateral side portion to a second lateral side portion, and alongitudinal dimension extending down a length of the implant strip,wherein, when the implant strip is in a coiled configuration between thefirst vertebra and the second vertebra, the first lateral side portionof the implant strip is configured to engage the first vertebra and thesecond lateral side portion of the implant strip is configured to engagethe second vertebra, and wherein the implant strip includes a firstsurface between the first lateral side portion and the second lateralside portion, and a second surface opposite to the first surface andbetween the first lateral side portion and the second lateral sideportion; and a separating portion made of a polymer and disposed at thefirst surface of the implant strip, wherein, in the coiledconfiguration, the separating portion is disposed between the firstinner coil and the second outer coil, and wherein the separating portioncovers less than an area of the first surface of the implant strip so asto provide gaps between coils of the first lateral side portion of theimplant strip when the implant strip is in the coiled configuration. 2.The spinal prosthesis according to claim 1, wherein the separatingportion comprises a plurality of protrusions on the first surface of theimplant strip.
 3. The spinal prosthesis according to claim 2, whereinthe protrusions are associated with corresponding divots on the opposingsecond surface of the implant strip.
 4. The spinal prosthesis accordingto claim 2, wherein the opposing second surface of the implant strip issubstantially smooth.
 5. The spinal prosthesis according to claim 2,wherein each protrusion of the plurality of protrusions is shaped as ahalf-sphere.
 6. The spinal prosthesis according to claim 5, wherein eachprotrusion of the plurality of protrusions is shaped and sizedsubstantially similarly.
 7. The spinal prosthesis according to claim 2,wherein each protrusion of the plurality of protrusions has a widthmeasured across the first surface of the implant strip and is spacedapart from adjacent protrusions distances greater than the width.
 8. Thespinal prosthesis according to claim 2, further comprising a secondplurality of protrusions disposed on the second surface of the implantstrip.
 9. The spinal prosthesis according to claim 2, wherein theplurality of protrusions each protrude from the first surfacesubstantially the same height, such that, in the coiled configuration,the plurality of protrusions separate the first inner coil and thesecond outer coil by a radial distance equal to the same height.
 10. Thespinal prosthesis according to claim 2, wherein each of the plurality ofprotrusions is distinct and spaced apart from adjacent protrusions. 11.The spinal prosthesis according to claim 1, wherein the separatingportion comprises a separating strip having a lateral dimension lessthan the lateral dimension of the implant strip.
 12. The spinalprosthesis according to claim 11, further comprising a second separatingstrip made of a polymer and disposed at the second surface of theimplant strip.
 13. The spinal prosthesis according to claim 1, furthercomprising a bone growth promoting agent disposed in the gaps betweenthe coils of the first lateral side portion of the implant strip. 14.The spinal prosthesis according to claim 1, further comprising a bonegrowth promoting paste configured to be applied in the gaps between thecoils of the first lateral side portion of the implant strip.
 15. Thespinal prosthesis according to claim 1, wherein the first lateral sideportion comprises a plurality of teeth.
 16. The spinal prosthesisaccording to claim 15, wherein the plurality of teeth has aconfiguration selected from the group consisting essentially of asaw-toothed shape, a rounded shape, a substantially dull shape, asubstantially sharp shape, irregularly spaced teeth, and regularlyspaced teeth.
 17. The spinal prosthesis according to claim 15, whereinthe second lateral side portion comprises a second plurality of teeth.18. A spinal prosthesis comprising: an implant strip made of metal andconfigured for insertion between a first vertebra and a second vertebra,wherein the implant strip forms a first inner coil and a second outercoil that coils around the first inner coil, wherein the implant stripincludes a lateral dimension extending in a lateral direction from afirst lateral side portion to a second lateral side portion, and alongitudinal dimension extending down a length of the implant strip,wherein, when the implant strip is in a coiled configuration between thefirst vertebra and the second vertebra, the first lateral side portionof the implant strip is configured to engage the first vertebra and thesecond lateral side portion of the implant strip is configured to engagethe second vertebra, and wherein the implant strip includes a firstsurface between the first lateral side portion and the second lateralside portion, and a second surface opposite to the first surface andbetween the first lateral side portion and the second lateral sideportion; and a separating portion made of a polymer and disposed at thefirst surface of the implant strip, wherein, in the coiledconfiguration, the separating portion is disposed between the firstinner coil and the second outer coil, and wherein the separating portionis spaced apart in the lateral direction from the first and secondlateral side portions of the implant strip so as to provide gaps betweencoils of each of the first and second lateral side portions of theimplant strip when the implant strip is in the coiled configuration;wherein the implant strip is made of metal and the separating portion ismade of a polymer.
 19. A spinal prosthesis comprising: an implant stripconfigured for insertion between a first vertebra and a second vertebra,wherein the implant strip forms a first inner coil and a second outercoil that coils around the first inner coil, wherein the implant stripincludes a lateral dimension extending in a lateral direction from afirst lateral side portion to a second lateral side portion, and alongitudinal dimension extending down a length of the implant strip,wherein, when the implant strip is in a coiled configuration between thefirst vertebra and the second vertebra, the first lateral side portionof the implant strip is configured to engage the first vertebra and thesecond lateral side portion of the implant strip is configured to engagethe second vertebra, wherein the implant strip includes a first surfacebetween the first lateral side portion and the second lateral sideportion, and a second surface opposite to the first surface and betweenthe first lateral side portion and the second lateral side portion, andwherein the implant strip is made of a shape-memory material that biasesthe implant strip to coil into the coiled configuration; and aseparating portion disposed at the first surface of the implant strip,wherein, in the coiled configuration, the separating portion is disposedbetween the first inner coil and the second outer coil, and wherein theseparating portion is spaced apart in the lateral direction from thefirst lateral side portion of the implant strip so as to provide gapsbetween coils of the first lateral side portion of the implant stripwhen the implant strip is in the coiled configuration.